The number of Ganesha's arms varies; his best-known forms have between two and sixteen arms. Many depictions of Ganesha feature four arms, which is mentioned in Puranic sources and codified as a standard form in some iconographic texts. His earliest images had two arms. Forms with 14 and 20 arms appeared in Central India during the 9th and the 10th centuries. The serpent is a common feature in Ganesha iconography and appears in many forms. According to the Ganesha Purana, Ganesha wrapped the serpent Vasuki around his neck. Other depictions of snakes include use as a sacred thread (IAST: yajñyopavīta) wrapped around the stomach as a belt, held in a hand, coiled at the ankles, or as a throne. Upon Ganesha's forehead may be a third eye or the sectarian mark (IAST: tilaka), which consists of three horizontal lines. The Ganesha Purana prescribes a tilaka mark as well as a crescent moon on the forehead. A distinct form of Ganesha called Bhalachandra (IAST: bhālacandra; "Moon on the Forehead") includes that iconographic element.

Ganesha is often described as red in colour. Specific colours are associated with certain forms. Many examples of color associations with specific meditation forms are prescribed in the Sritattvanidhi, a treatise on Hindu iconography. For example, white is associated with his representations as Heramba-Ganapati and Rina-Mochana-Ganapati (Ganapati Who Releases from Bondage). Ekadanta-Ganapati is visualised as blue during meditation in that form.

The earliest Ganesha images are without a vahana (mount/vehicle). Of the eight incarnations of Ganesha described in the Mudgala Purana, Ganesha uses a mouse (shrew) in five of them, a lion in his incarnation as Vakratunda, a peacock in his incarnation as Vikata, and Shesha, the divine serpent, in his incarnation as Vighnaraja. Mohotkata uses a lion, Mayūreśvara uses a peacock, Dhumraketu uses a horse, and Gajanana uses a mouse, in the four incarnations of Ganesha listed in the Ganesha Purana. Jain depictions of Ganesha show his vahana variously as a mouse, elephant, tortoise, ram, or peacock.

Ganesha is often shown riding on or attended by a mouse. Martin-Dubost says that the rat began to appear as the principal vehicle in sculptures of Ganesha in central and western India during the 7th century; the rat was always placed close to his feet. The mouse as a mount first appears in written sources in the Matsya Purana and later in the Brahmananda Purana and Ganesha Purana, where Ganesha uses it as his vehicle in his last incarnation. The Ganapati Atharvashirsa includes a meditation verse on Ganesha that describes the mouse appearing on his flag. The names Mūṣakavāhana (mouse-mount) and Ākhuketana (rat-banner) appear in the Ganesha Sahasranama.

The mouse is interpreted in several ways. According to Grimes, "Many, if not most of those who interpret Gaṇapati's mouse, do so negatively; it symbolizes tamoguṇa as well as desire". Along these lines, Michael Wilcockson says it symbolises those who wish to overcome desires and be less selfish. Krishan notes that the rat is destructive and a menace to crops. The Sanskrit word mūṣaka (mouse) is derived from the root mūṣ (stealing, robbing). It was essential to subdue the rat as a destructive pest, a type of vighna (impediment) that needed to be overcome. According to this theory, showing Ganesha as master of the rat demonstrates his function as Vigneshvara (Lord of Obstacles) and gives evidence of his possible role as a folk grāma-devatā (village deity) who later rose to greater prominence. Martin-Dubost notes a view that the rat is a symbol suggesting that Ganesha, like the rat, penetrates even the most secret places.

Ganesha is Vighneshvara (Vighnaraja, Marathi – Vighnaharta), the Lord of Obstacles, both of a material and spiritual order. He is popularly worshipped as a remover of obstacles, though traditionally he also places obstacles in the path of those who need to be checked. Hence, he is often worshipped by the people before they begin anything new. Paul Courtright says that Ganesha's dharma and his raison d'être is to create and remove obstacles.

Krishan notes that some of Ganesha's names reflect shadings of multiple roles that have evolved over time. Dhavalikar ascribes the quick ascension of Ganesha in the Hindu pantheon, and the emergence of the Ganapatyas, to this shift in emphasis from vighnakartā (obstacle-creator) to vighnahartā (obstacle-averter). However, both functions continue to be vital to his character.

Ganesha is considered to be the Lord of letters and learning. In Sanskrit, the word buddhi is an active noun that is variously translated as intelligence, wisdom, or intellect. The concept of buddhi is closely associated with the personality of Ganesha, especially in the Puranic period, when many stories stress his cleverness and love of intelligence. One of Ganesha's names in the Ganesha Purana and the Ganesha Sahasranama is Buddhipriya. This name also appears in a list of 21 names at the end of the Ganesha Sahasranama that Ganesha says are especially important. The word priya can mean "fond of", and in a marital context it can mean "lover" or "husband", so the name may mean either "Fond of Intelligence" or "Buddhi's Husband".

Ganesha is identified with the Hindu mantra Om. The term oṃkārasvarūpa (Om is his form), when identified with Ganesha, refers to the notion that he personifies the primal sound. The Ganapati Atharvashirsa attests to this association. Chinmayananda translates the relevant passage as follows:

(O Lord Ganapati!) You are (the Trimurti) Brahma, Vishnu, and Mahesa. You are Indra. You are fire [Agni] and air [Vāyu]. You are the sun [Sūrya] and the moon [Chandrama]. You are Brahman. You are (the three worlds) Bhuloka [earth], Antariksha-loka [space], and Swargaloka [heaven]. You are Om. (That is to say, You are all this).

Some devotees see similarities between the shape of Ganesha's body in iconography and the shape of Om in the Devanāgarī and Tamil scripts.

According to Kundalini yoga, Ganesha resides in the first chakra, called Muladhara (mūlādhāra). Mula means "original, main"; adhara means "base, foundation". The muladhara chakra is the principle on which the manifestation or outward expansion of primordial Divine Force rests. This association is also attested to in the Ganapati Atharvashirsa. Courtright translates this passage as follows: "You continually dwell in the sacral plexus at the base of the spine [mūlādhāra cakra]." Thus, Ganesha has a permanent abode in every being at the Muladhara. Ganesha holds, supports and guides all other chakras, thereby "governing the forces that propel the wheel of life".

Though Ganesha is popularly held to be the son of Shiva and Parvati, the Puranic texts give different versions about his birth. In some he was created by Parvati, or by Shiva or created by Shiva and Parvati, in another he appeared mysteriously and was discovered by Shiva and Parvati or he was born from the elephant headed goddess Malini after she drank Parvati's bath water that had been thrown in the river.

The family includes his brother, the god of war, Kartikeya, who is also called Skanda and Murugan. Regional differences dictate the order of their births. In northern India, Skanda is generally said to be the elder, while in the south, Ganesha is considered the firstborn. In northern India, Skanda was an important martial deity from about 500 BCE to about 600 CE, after which worship of him declined significantly. As Skanda fell, Ganesha rose. Several stories tell of sibling rivalry between the brothers and may reflect sectarian tensions.

Ganesha's marital status, the subject of considerable scholarly review, varies widely in mythological stories. One pattern of myths identifies Ganesha as an unmarried brahmachari. This view is common in southern India and parts of northern India. Another popularly-accepted mainstream pattern associates him with the concepts of Buddhi (intellect), Siddhi (spiritual power), and Riddhi (prosperity); these qualities are personified as goddesses, said to be Ganesha's wives. He also may be shown with a single consort or a nameless servant (Sanskrit: daşi). Another pattern connects Ganesha with the goddess of culture and the arts, Sarasvati or Śarda (particularly in Maharashtra). He is also associated with the goddess of luck and prosperity, Lakshmi. Another pattern, mainly prevalent in the Bengal region, links Ganesha with the banana tree, Kala Bo.

The Shiva Purana says that Ganesha had begotten two sons: Kşema (safety) and Lābha (profit). In northern Indian variants of this story, the sons are often said to be Śubha (auspiciousness) and Lābha. The 1975 Hindi film Jai Santoshi Maa shows Ganesha married to Riddhi and Siddhi and having a daughter named Santoshi Ma, the goddess of satisfaction. This story has no Puranic basis, but Anita Raina Thapan and Lawrence Cohen cite Santoshi Ma's cult as evidence of Ganesha's continuing evolution as a popular deity.

Ganesha is worshipped on many religious and secular occasions; especially at the beginning of ventures such as buying a vehicle or starting a business. K.N Soumyaji says, "there can hardly be a [Hindu] home [in India] which does not house an idol of Ganapati. ... Ganapati, being the most popular deity in India, is worshipped by almost all castes and in all parts of the country". Devotees believe that if Ganesha is propitiated, he grants success, prosperity and protection against adversity.

Ganesha is a non-sectarian deity. Hindus of all denominations invoke him at the beginning of prayers, important undertakings, and religious ceremonies. Dancers and musicians, particularly in southern India, begin art performances such as the Bharatanatyam dance with a prayer to Ganesha. Mantras such as Om Shri Gaṇeshāya Namah (Om, salutation to the Illustrious Ganesha) are often used. One of the most famous mantras associated with Ganesha is Om Gaṃ Ganapataye Namah (Om, Gaṃ, Salutation to the Lord of Hosts).

Devotees offer Ganesha sweets such as modaka and small sweet balls called laddus. He is often shown carrying a bowl of sweets, called a modakapātra. Because of his identification with the color red, he is often worshipped with red sandalwood paste (raktachandana) or red flowers. Dūrvā grass (Cynodon dactylon) and other materials are also used in his worship.

Festivals associated with Ganesh are Ganesha Chaturthi or Vināyaka chaturthī in the śuklapakṣa (the fourth day of the waxing moon) in the month of Bhadrapada (August/September) and the Ganesh Jayanti (Ganesha's birthday) celebrated on the cathurthī of the śuklapakṣa (fourth day of the waxing moon) in the month of magha (January/February)."

An annual festival honours Ganesha for ten days, starting on Ganesha Chaturthi, which typically falls in late August or early September. The festival begins with people bringing in clay idols of Ganesha, symbolising the god's visit. The festival culminates on the day of Ananta Chaturdashi, when the idols (murtis) are immersed in the most convenient body of water. Some families have a tradition of immersion on the 2nd, 3rd, 5th, or 7th day. In 1893, Lokmanya Tilak transformed this annual Ganesha festival from private family celebrations into a grand public event. He did so "to bridge the gap between the Brahmins and the non-Brahmins and find an appropriate context in which to build a new grassroots unity between them" in his nationalistic strivings against the British in Maharashtra. Because of Ganesha's wide appeal as "the god for Everyman", Tilak chose him as a rallying point for Indian protest against British rule. Tilak was the first to install large public images of Ganesha in pavilions, and he established the practice of submerging all the public images on the tenth day.

Today, Hindus across India celebrate the Ganapati festival with great fervour, though it is most popular in the state of Maharashtra. The festival also assumes huge proportions in Mumbai, Pune, and in the surrounding belt of Ashtavinayaka temples.

In Hindu temples, Ganesha is depicted in various ways: as a subordinate deity (pãrśva-devatã); as a deity related to the principal deity (parivāra-devatã); or as the principal deity of the temple (pradhāna). As the god of transitions, he is placed at the doorway of many Hindu temples to keep out the unworthy, which is analogous to his role as Parvati's doorkeeper. In addition, several shrines are dedicated to Ganesha himself, of which the Ashtavinayak (Sanskrit: अष्टविनायक; aṣṭavināyaka; lit. "eight Ganesha (shrines)") in Maharashtra are particularly well known. Located within a 100-kilometer radius of the city of Pune, each of the eight shrines celebrates a particular form of Ganapati, complete with its own lore. The eight shrines are: Morgaon, Siddhatek, Pali, Mahad, Theur, Lenyadri, Ozar and Ranjangaon.

There are many other important Ganesha temples at the following locations: Siddhivinayak temple in Mumbai, Ganpatipule temple at Ganpatipule, Binkhambi Ganesh mandir in Kolhapur, Jai Vinayak temple in Jaigad, Ratnagiri, Wai in Maharashtra; Ujjain in Madhya Pradesh; Jodhpur, Nagaur and Raipur (Pali) in Rajasthan; Baidyanath in Bihar; Baroda, Dholaka, and Valsad in Gujarat and Dhundiraj Temple in Varanasi, Uttar Pradesh. Prominent Ganesha temples in southern India include the following: Kanipakam in Andhra Pradesh; the Rockfort Ucchi Pillayar Temple at Tiruchirapalli, Puliakulam Munthi Vinayagar Temple at Coimbatore and Karpaga Vinayagar Temple in Pillaiyarpatti which is a town named after Ganesha in Tamil Nadu; Kottarakkara, Pazhavangadi, Kasargod in Kerala; Hampi, and Idagunji in Karnataka; and Bhadrachalam in Telangana.

T. A. Gopinatha notes, "Every village however small has its own image of Vighneśvara (Vigneshvara) with or without a temple to house it in. At entrances of villages and forts, below pīpaḹa (Sacred fig) trees ... in a niche ... in temples of Viṣṇu (Vishnu) as well as Śiva (Shiva) and also in separate shrines specially constructed in Śiva temples ... the figure of Vighneśvara is invariably seen." Ganesha temples have also been built outside of India, including Southeast Asia, Nepal (including the four Vinayaka shrines in the Kathmandu Valley), and in several western countries.

An elephant–headed anthropomorphic figure on Indo-Greek coins from the 1st century BCE has been proposed by some scholars to be "incipient Ganesha", but this has been strongly contested. Others have suggested Ganesha may have been an emerging deity in India and southeast Asia around the 2nd century CE based on the evidence from archaeological excavations in Mathura and outside India. First terracotta images of Ganesha are from 1st century CE found in Ter, Pal, Verrapuram, and Chandraketugarh. These figures are small, with an elephant head, two arms, and chubby physique. The earliest Ganesha icons in stone were carved in Mathura during Kushan times (2nd–3rd centuries CE).

Ganesha appeared in his classic form as a clearly-recognizable deity with well-defined iconographic attributes in the early 4th to 5th centuries CE. Some of the earliest known Ganesha images include two images found in eastern Afghanistan. The first image was discovered in the ruins north of Kabul along with those of Surya and Shiva. It is dated to the 4th century. The second image found in Gardez, the Gardez Ganesha, has an inscription on Ganesha pedestal that has helped date it to the 5th century. Another Ganesha sculpture is embedded in the walls of Cave 6 of the Udayagiri Caves in Madhya Pradesh. This is dated to the 5th century. An early iconic image of Ganesha with elephant head, a bowl of sweets and a goddess sitting in his lap has been found in the ruins of the Bhumara Temple in Madhya Pradesh, and this is dated to the 5th-century Gupta period. Other recent discoveries, such as one from Ramgarh Hill, are also dated to the 4th or 5th century. An independent cult with Ganesha as the primary deity was well established by about the 10th century. Narain summarises the lack of evidence about Ganesha's history before the 5th century as follows:

What is inscrutable is the somewhat dramatic appearance of Gaṇeśa on the historical scene. His antecedents are not clear. His wide acceptance and popularity, which transcend sectarian and territorial limits, are indeed amazing. On the one hand, there is the pious belief of the orthodox devotees in Gaṇeśa's Vedic origins and in the Purāṇic explanations contained in the confusing, but nonetheless interesting, mythology. On the other hand, there are doubts about the existence of the idea and the icon of this deity" before the fourth to fifth century A.D. ... [I]n my opinion, indeed there is no convincing evidence [in ancient Brahmanic literature] of the existence of this divinity prior to the fifth century.

The evidence for more ancient Ganesha, suggests Narain, may reside outside Brahmanic or Sanskritic traditions, or outside geocultural boundaries of India. Ganesha appears in China by the 6th century, states Brown, and his artistic images in temple setting as "remover of obstacles" in South Asia appear by about 400 CE. He is, states Bailey, recognised as goddess Parvati's son and integrated into Shaivism theology by early centuries of the common era.

Courtright reviews various speculative theories about the early history of Ganesha, including supposed tribal traditions and animal cults, and dismisses all of them in this way:

In this search for a historical origin for Gaṇeśa, some have suggested precise locations outside the Brāhmaṇic tradition.... These historical locations are intriguing to be sure, but the fact remains that they are all speculations, variations on the Dravidian hypothesis, which argues that anything not attested to in the Vedic and Indo-European sources must have come into Brāhmaṇic religion from the Dravidian or aboriginal populations of India as part of the process that produced Hinduism out of the interactions of the Aryan and non-Aryan populations. There is no independent evidence for an elephant cult or a totem; nor is there any archaeological data pointing to a tradition prior to what we can already see in place in the Purāṇic literature and the iconography of Gaṇeśa.

Thapan's book on the development of Ganesha devotes a chapter to speculations about the role elephants had in early India but concludes that "although by the second century CE the elephant-headed yakṣa form exists it cannot be presumed to represent Gaṇapati-Vināyaka. There is no evidence of a deity by this name having an elephant or elephant-headed form at this early stage. Gaṇapati-Vināyaka had yet to make his debut."

The Pashupati seal (c. 2300 BCE - 2000 BCE) depicts 4 animals including an elephant around a deity who is claimed by some to be Shiva. Brown notes that this seal indicates the sacredness of elephants before Vedic period. One theory of the origin of Ganesha is that he gradually came to prominence in connection with the four Vinayakas (Vināyakas). In the Yajurveda, the Vināyakas were a group of four troublesome demons who created obstacles and difficulties but who were easily propitiated. The name Vināyaka is a common name for Ganesha both in the Purāṇas and in Buddhist Tantras. Krishan is one of the academics who accept this view, stating flatly of Ganesha, "He is a non-Vedic god. His origin is to be traced to the four Vināyakas, evil spirits, of the Mānavagŗhyasūtra (7th–4th century BCE) who cause various types of evil and suffering". Depictions of elephant-headed human figures, which some identify with Ganesha, appear in Indian art and coinage as early as the 2nd century. According to Ellawala, the elephant-headed Ganesha as lord of the Ganas was known to the people of Sri Lanka in the early pre-Christian era.

The title "Leader of the group" (Sanskrit: gaṇapati) occurs twice in the Rig Veda, but in neither case does it refer to the modern Ganesha. The term appears in RV 2.23.1 as a title for Brahmanaspati, according to commentators. While this verse doubtless refers to Brahmanaspati, it was later adopted for worship of Ganesha and is still used today. In rejecting any claim that this passage is evidence of Ganesha in the Rig Veda, Ludo Rocher says that it "clearly refers to Bṛhaspati—who is the deity of the hymn—and Bṛhaspati only". Equally clearly, the second passage (RV 10.112.9) refers to Indra, who is given the epithet 'gaṇapati', translated "Lord of the companies (of the Maruts)." However, Rocher notes that the more recent Ganapatya literature often quotes the Rigvedic verses to give Vedic respectability to Ganesha.

The Sangam period Tamil poet Avvaiyar (3rd century BCE), invokes Ganesha while preparing the invitation to the three Tamil Kingdoms for giving away in marriage of Angavay and Sangavay of Ceylon in marriage to the King of Tirucovalur (pp. 57–59).

Two verses in texts belonging to Black Yajurveda, Maitrāyaṇīya Saṃhitā (2.9.1) and Taittirīya Āraṇyaka (10.1), appeal to a deity as "the tusked one" (Dantiḥ), "elephant-faced" (Hastimukha), and "with a curved trunk" (Vakratuṇḍa). These names are suggestive of Ganesha, and the 14th-century commentator Sayana explicitly establishes this identification. The description of Dantin, possessing a twisted trunk (vakratuṇḍa) and holding a corn-sheaf, a sugar cane, and a club, is so characteristic of the Puranic Ganapati that Heras says "we cannot resist to accept his full identification with this Vedic Dantin". However, Krishan considers these hymns to be post-Vedic additions. Thapan reports that these passages are "generally considered to have been interpolated". Dhavalikar says, "the references to the elephant-headed deity in the Maitrāyaṇī Saṃhitā have been proven to be very late interpolations, and thus are not very helpful for determining the early formation of the deity".

Ganesha does not appear in the Indian epic literature that is dated to the Vedic period. A late interpolation to the epic poem Mahabharata (1.1.75–79) says that the sage Vyasa (Vyāsa) asked Ganesha to serve as his scribe to transcribe the poem as he dictated it to him. Ganesha agreed but only on the condition that Vyasa recites the poem uninterrupted, that is, without pausing. The sage agreed but found that to get any rest he needed to recite very complex passages so Ganesha would have to ask for clarifications. The story is not accepted as part of the original text by the editors of the critical edition of the Mahabharata, in which the twenty-line story is relegated to a footnote in an appendix. The story of Ganesha acting as the scribe occurs in 37 of the 59 manuscripts consulted during the preparation of the critical edition. Ganesha's association with mental agility and learning is one reason he is shown as scribe for Vyāsa's dictation of the Mahabharata in this interpolation. Richard L. Brown dates the story to the 8th century, and Moriz Winternitz concludes that it was known as early as c. 900, but it was not added to the Mahabharata some 150 years later. Winternitz also notes that a distinctive feature in South Indian manuscripts of the Mahabharata is their omission of this Ganesha legend. The term vināyaka is found in some recensions of the Śāntiparva and Anuśāsanaparva that are regarded as interpolations. A reference to Vighnakartṛīṇām ("Creator of Obstacles") in Vanaparva is also believed to be an interpolation and does not appear in the critical edition.

Stories about Ganesha often occur in the Puranic corpus. Brown notes while the Puranas "defy precise chronological ordering", the more detailed narratives of Ganesha's life are in the late texts, c. 600–1300. Yuvraj Krishan says that the Puranic myths about the birth of Ganesha and how he acquired an elephant's head are in the later Puranas, which were composed of c. 600 onwards. He elaborates on the matter to say that references to Ganesha in the earlier Puranas, such as the Vayu and Brahmanda Puranas, are later interpolations made during the 7th-10th centuries.

In his survey of Ganesha's rise to prominence in Sanskrit literature, Ludo Rocher notes that:

Above all, one cannot help being struck by the fact that the numerous stories surrounding Gaṇeśa concentrate on an unexpectedly limited number of incidents. These incidents are mainly three: his birth and parenthood, his elephant head, and his single tusk. Other incidents are touched on in the texts, but to a far lesser extent.

Ganesha's rise to prominence was codified in the 9th century when he was formally included as one of the five primary deities of Smartism. The 9th-century philosopher Adi Shankara popularised the "worship of the five forms" (Panchayatana puja) system among orthodox Brahmins of the Smarta tradition. This worship practice invokes the five deities Ganesha, Vishnu, Shiva, Devi, and Surya. Adi Shankara instituted the tradition primarily to unite the principal deities of these five major sects on an equal status. This formalised the role of Ganesha as a complementary deity.

In the Ganapatya tradition founded in the Ganesha Purana and the Mudgala Purana, Ganesha is worshipped as one of the five principle deities along with Siva, Vishnu, the Sun, Ganesha, and the Goddess.

The date of composition for the Ganesha Purana and the Mudgala Purana—and their dating relative to one another—has sparked academic debate. Both works were developed over time and contain age-layered strata. Anita Thapan reviews comment about dating and provide her own judgment. "It seems likely that the core of the Ganesha Purana appeared around the twelfth and thirteenth centuries", she says, "but was later interpolated." Lawrence W. Preston considers the most reasonable date for the Ganesha Purana to be between 1100 and 1400, which coincides with the apparent age of the sacred sites mentioned by the text.

R.C. Hazra suggests that the Mudgala Purana is older than the Ganesha Purana, which he dates between 1100 and 1400. However, Phyllis Granoff finds problems with this relative dating and concludes that the Mudgala Purana was the last of the philosophical texts concerned with Ganesha. She bases her reasoning on the fact that, among other internal evidence, the Mudgala Purana specifically mentions the Ganesha Purana as one of the four Puranas (the Brahma, the Brahmanda, the Ganesha, and the Mudgala Puranas) which deal at length with Ganesha. While the kernel of the text must be old, it was interpolated until the 17th and 18th centuries as the worship of Ganapati became more important in certain regions. Another highly regarded scripture in the Ganapatya tradition, the Sanskrit Ganapati Atharvashirsa, was probably composed during the 16th or 17th century.

The Ganesha Sahasranama is part of the Puranic literature, and is a litany of a thousand names and attributes of Ganesha. Each name in the sahasranama conveys a different meaning and symbolises a different aspect of Ganesha. Versions of the Ganesha Sahasranama are found in the Ganesha Purana.

In Shri Vidya traditions, particularly in South Indian practices, Ganapathi in the form of Maha Ganapathi holds an important role as the remover of obstacles and is often invoked at the beginning of rituals. The Parashurama Kalpasutra, a key text in Srividya, dedicates a chapter to his worship called Ganapathi Krama, outlining specific methods for his invocation. Ganapathi is considered essential in ensuring the smooth progression of spiritual practices within the Srividya framework. His worship is integrated into rituals involving the Sri Chakra and other related practices.