Writing is the act of creating a persistent representation of human language. A writing system uses a set of symbols and rules to encode aspects of spoken language, such as its lexicon and syntax. However, written language may take on characteristics distinct from those of any spoken language.

Writing is a cognitive and social activity involving neuropsychological and physical processes. The outcome of this activity, also called "writing", and sometimes a "text", is a series of physically inscribed, mechanically transferred, or digitally represented symbols. The interpreter or activator of a text is called a "reader".

In general, writing systems do not constitute languages in and of themselves, but rather a means of encoding language such that it can be read by others across time and space. While not all languages use a writing system, those that do can complement and extend the capacities of spoken language by creating durable forms of language that can be transmitted across space (e.g. written correspondence) and stored over time (e.g. libraries or other public records). Writing can also have knowledge-transforming effects, since it allows humans to externalize their thinking in forms that are easier to reflect on, elaborate on, reconsider, and revise.

Any instance of writing involves a complex interaction among available tools, intentions, cultural customs, cognitive routines, genres, tacit and explicit knowledge, and the constraints and limitations of the writing system(s) deployed. Inscriptions have been made with fingers, styluses, quills, ink brushes, pencils, pens, and many styles of lithography; surfaces used for these inscriptions include stone tablets, clay tablets, bamboo slats, papyrus, wax tablets, vellum, parchment, paper, copperplate, slate, porcelain, and other enameled surfaces. The Incas used knotted cords known as quipu (or khipu) for keeping records.

The typewriter and subsequently various digital word processors have recently become widespread writing tools, and studies have compared the ways in which writers have framed the experience of writing with such tools as compared with the pen or pencil.

Advancements in natural language processing and natural language generation have resulted in software capable of producing certain forms of formulaic writing (e.g., weather forecasts and brief sports reporting) without the direct involvement of humans after initial configuration or, more commonly, to be used to support writing processes such as generating initial drafts, producing feedback with the help of a rubric, copy-editing, and helping translation.

Writing technologies from different eras coexist easily in many homes and workplaces. During the course of a day or even a single episode of writing, for example, a writer might instinctively switch among a pencil, a touchscreen, a text-editor, a whiteboard, a legal pad, and adhesive notes as different purposes arise.

As human societies emerged, collective motivations for the development of writing were driven by pragmatic exigencies like keeping track of produce and other wealth, recording history, maintaining culture, codifying knowledge through curricula and lists of texts deemed to contain foundational knowledge (e.g. The Canon of Medicine) or artistic value (e.g. the literary canon), organizing and governing societies through texts including legal codes, census records, contracts, deeds of ownership, taxation, trade agreements, and treaties. As Charles Bazerman explains, the "marking of signs on stones, clay, paper, and now digital memories—each more portable and rapidly traveling than the previous—provided means for increasingly coordinated and extended action as well as memory across larger groups of people over time and space." For example, around the 4th millennium BC, the complexity of trade and administration in Mesopotamia outgrew human memory, and writing became a more dependable method for creating permanent records of transactions. On the other hand, writing in both ancient Egypt and Mesoamerica may have evolved through the political necessity to manage the calendar for recording historical and environmental events. Further innovations included more uniform, predictable, and widely dispersed legal systems, the distribution of accessible versions of sacred texts, and furthering practices of scientific inquiry and knowledge management, all of which were largely reliant on portable and easily reproducible forms of inscribed language. The history of writing is co-extensive with uses of writing and the elaboration of activity systems that give rise to and circulate writing.

Individual motivations for writing include improvised additional capacity for the limitations of human memory (e.g. to-do lists, recipes, reminders, logbooks, maps, the proper sequence for a complicated task or important ritual), dissemination of ideas and coordination (e.g. essays, monographs, broadsides, plans, petitions, or manifestos), creativity and storytelling, maintaining kinship and other social networks, business correspondence regarding goods and services, and life writing (e.g. a diary or journal).

The global spread of digital communication systems such as e-mail and social media has made writing an increasingly important feature of daily life, where these systems mix with older technologies like paper, pencils, whiteboards, printers, and copiers. Substantial amounts of everyday writing characterize most workplaces in developed countries. In many occupations (e.g. law, accounting, software design, human resources), written documentation is not only the main deliverable but also the mode of work itself. Even in occupations not typically associated with writing, routine records management has most employees writing at least some of the time.

Some professions are typically associated with writing, such as literary authors, journalists, and technical writers, but writing is pervasive in most modern forms of work, civic participation, household management, and leisure activities.

Writing permeates everyday commerce. For example, in the course of an afternoon, a wholesaler might receive a written inquiry about the availability of a product line, then communicate with suppliers and fabricators through work orders and purchase agreements, correspond via email to affirm shipping availability with a drayage company, write an invoice, and request proof of receipt in the form of a written signature. At a much larger scale, modern systems of finances, banking, and business rest on many forms of written documents—including written regulations, policies, and procedures; the creation of reports and other monitoring documents to make, evaluate, and provide accountability for decisions and operations; the creation and maintenance of records; internal written communications within departments to coordinate work; written communications that comprise work products presented to other departments and to clients; and external communications to clients and the public. Business and financial organizations also rely on many written legal documents, such as contracts, reports to government agencies, tax records, and accounting reports. Financial institutions and markets that hold, transmit, trade, insure, or regulate holdings for clients or other institutions are particularly dependent on written records (though now often in digital form) to maintain the integrity of their roles.

Many modern systems of government are organized and sanctified through written constitutions at the national and sometimes state or other organizational levels. Written rules and procedures typically guide the operations of the various branches, departments, and other bodies of government, which regularly produce reports and other documents as work products and to account for their actions. In addition to legislatures that draft and pass laws, these laws are administered by an executive branch, which can present further written regulations specifying the laws and how they are carried out. Governments at different levels also typically maintain written records on citizens concerning identities, life events such as births, deaths, marriages, and divorces, the granting of licenses for controlled activities, criminal charges, traffic offenses, and other penalties small and large, and tax liability and payments.

Research undertaken in academic disciplines is typically published as articles in journals or within book-length monographs. Arguments, experiments, observational data, and other evidence collated in the course of research is represented in writing, and serves as the basis for later work. Data collection and drafting of manuscripts may be supported by grants, which usually require proposals establishing the value of such work and the need for funding. The data and procedures are also typically collected in lab notebooks or other preliminary files. Preprints of potential publications may also be presented at academic or disciplinary conferences or on publicly accessible web servers to gain peer feedback and build interest in the work. Prior to official publication, these documents are typically read and evaluated by peer review from appropriate experts, who determine whether the work is of sufficient value and quality to be published.

Publication does not establish the claims or findings of work as being authoritatively true, only that they are worth the attention of other specialists. As the work appears in review articles, handbooks, textbooks, or other aggregations, and others cite it in the advancement of their own research, does it become codified as contingently reliable knowledge.

News and news reporting are central to citizen engagement and knowledge of many spheres of activity people may be interested in about the state of their community, including the actions and integrity of their governments and government officials, economic trends, natural disasters and responses to them, international geopolitical events, including conflicts, but also sports, entertainment, books, and other leisure activities. While news and newspapers have grown rapidly from the eighteenth to the twentieth centuries, the changing economics and ability to produce and distribute news have brought about radical and rapid challenges to journalism and the consequent organization of citizen knowledge and engagement. These changes have also created challenges for journalism ethics that have been developed over the past century.

Formal education is the social context most strongly associated with the learning of writing, and students may carry these particular associations long after leaving school. Alongside the writing that students read (in the forms of textbooks, assigned books, and other instructional materials as well as self-selected books) students do much writing within schools at all levels, on subject exams, in essays, in taking notes, in doing homework, and in formative and summative assessments.  Some of this is explicitly directed toward the learning of writing, but much is focused more on subject learning.

Writing systems may be broadly classified according to what units of language are represented by its symbols: alphabets and syllabaries generally represent a language's sounds of speech (phonemes and syllables respectively)—while logographies represent a language's units of meaning (words or morphemes), though these are still associated by readers with their given pronunciations in the corresponding spoken language.

A logography is written using logograms—written characters which represent individual words or morphemes. For example, in Mayan, the glyph for "fin", pronounced ka, was also used to represent the syllable ka whenever the pronunciation of a logogram needed to be indicated. Many logograms have an ideographic component (Chinese "radicals", hieroglyphic "determiners"). In Chinese, about 90% of characters are compounds of a semantic (meaning) element called a radical with an existing character to indicate the pronunciation, called a phonetic. However, such phonetic elements complement the logographic elements, rather than vice versa.

The main logographic system in use today is Chinese characters, used with some modification for the various languages or dialects of China, Japan, and sometimes in Korean, although in South and North Korea, the phonetic Hangul system is mainly used. Other logographic systems include cuneiform and Maya.

A syllabary is a set of written symbols that represent syllables, typically a consonant followed by a vowel, or just a vowel alone. In some scripts more complex syllables (such as consonant-vowel-consonant, or consonant-consonant-vowel) may have dedicated glyphs. Phonetically similar syllables are not written similarly. For instance, the syllable "ka" may look nothing like the syllable "ki", nor will syllables with the same vowels be similar.

Syllabaries are best suited to languages with a relatively simple syllable structure, such as Japanese. Other languages that use syllabic writing include Mycenaean Greek (Linear B), Cherokee, the Ndjuka creole language of Suriname, and the Vai language of Liberia.

An alphabet is a set of written symbols that represent consonants and vowels. In a perfectly phonological alphabet, the letters would correspond perfectly to the language's phonemes. Thus, a writer could predict the spelling of a word given its pronunciation, and a speaker could predict the pronunciation of a word given its spelling. However, as languages often evolve independently of their writing systems, and writing systems have been borrowed for languages they were not designed for, the degree to which letters of an alphabet correspond to phonemes of a language varies greatly from one language to another and even within a single language.

In most of the alphabets of the Middle East, it is usually only the consonants of a word that are written, although vowels may be indicated by the addition of various diacritical marks. Writing systems based primarily on writing just consonants phonemes date back to the hieroglyphs of ancient Egypt. Such systems are called abjads, derived from the Arabic word for 'alphabet', or consonantaries.

In most of the alphabets of India and Southeast Asia, vowels are indicated through diacritics or modification of the shape of the consonant. These are called abugidas. Some abugidas, such as Geʽez and the Canadian Aboriginal syllabics, are learned by children as syllabaries, and so are often called "syllabics". However, unlike true syllabaries, there is not an independent glyph for each syllable.

While research into the development of writing during the Neolithic is ongoing, the current consensus is that it first evolved from economic necessity in the ancient Near East. Writing most likely began as a consequence of political expansion in ancient cultures, which needed reliable means for transmitting information, maintaining financial accounts, keeping historical records, and similar activities. Around the 4th millennium BC, the complexity of trade and administration outgrew the power of memory, and writing became a more dependable method of recording and presenting transactions in a permanent form.

The invention of the first writing systems is roughly contemporary with the emergence of civilisations and the beginning of the Bronze Age during the late 4th millennium BC. Cuneiform used to write the Sumerian language and Egyptian hieroglyphs are generally considered the earliest writing systems, both emerging out of ancestral proto-writing systems between 3400 and 3300 BC, with earliest coherent texts from c. 2600 BC. It is generally agreed that Sumerian writing was an independent invention; however, it is debated whether Egyptian writing was developed completely independently of Sumerian, or was a case of cultural diffusion.

Archaeologist Denise Schmandt-Besserat determined the link between previously uncategorized clay "tokens", the oldest of which have been found in the Zagros region of Iran, and cuneiform, the first known writing. Around 8000 BC, Mesopotamians began using clay tokens to count their agricultural and manufactured goods. Later they began placing these tokens inside large, hollow clay containers (bulla, or globular envelopes) which were then sealed. The quantity of tokens in each container came to be expressed by impressing, on the container's surface, one picture for each instance of the token inside. They next dispensed with the tokens, relying solely on symbols for the tokens, drawn on clay surfaces. To avoid making a picture for each instance of the same object (for example: 100 pictures of a hat to represent 100 hats), they counted the objects by using various small marks. In this way the Sumerians added "a system for enumerating objects to their incipient system of symbols".

The original Mesopotamian writing system was derived c. 3200 BC from this method of keeping accounts. By the end of the 4th millennium BC, the Mesopotamians were using a triangular-shaped stylus pressed into soft clay to record numbers. This system was gradually augmented with using a sharp stylus to indicate what was being counted by means of pictographs. Round and sharp styluses were gradually replaced for writing by wedge-shaped styluses (hence the term cuneiform), at first only for logograms, but by the 29th century BC also for phonetic elements. Around 2700 BC, cuneiform began to represent syllables of spoken Sumerian. About that time, Mesopotamian cuneiform became a general purpose writing system for logograms, syllables, and numbers. This script was adapted to another Mesopotamian language, the East Semitic Akkadian (Assyrian and Babylonian) c. 2600 BC, and then to others such as Elamite, Hattian, Hurrian and Hittite. Scripts similar in appearance to this writing system include those for Ugaritic and Old Persian. With the adoption of Aramaic as the lingua franca of the Neo-Assyrian Empire (911–609 BC), Old Aramaic was also adapted to Mesopotamian cuneiform. The last cuneiform scripts in Akkadian discovered thus far date from the 1st century AD.

The earliest known hieroglyphs are about 5,200 years old, such as the clay labels of a Predynastic ruler called "Scorpion I" (Naqada IIIA period, c. 32nd century BC) recovered at Abydos (modern Umm el-Qa'ab) in 1998 or the Narmer Palette, dating to c. 3100 BC, and several recent discoveries that may be slightly older, though these glyphs were based on a much older artistic rather than written tradition. The hieroglyphic script was logographic with phonetic adjuncts that included an effective alphabet. The world's oldest deciphered sentence was found on a seal impression found in the tomb of Seth-Peribsen at Abydos, which dates from the Second Dynasty (28th or 27th century BC). There are around 800 hieroglyphs dating back to the Old Kingdom, Middle Kingdom and New Kingdom Eras. By the Greco-Roman period, there are more than 5,000.

Writing was very important in maintaining the Egyptian empire, and literacy was concentrated among an educated elite of scribes. Only people from certain backgrounds were allowed to train to become scribes, in the service of temple, pharaonic, and military authorities. The hieroglyph system was always difficult to learn, but in later centuries was purposely made even more so, as this preserved the scribes' status.

The world's oldest known alphabet appears to have been developed by Canaanite turquoise miners in the Sinai desert around the mid-19th century BC. Around 30 crude inscriptions have been found at a mountainous Egyptian mining site known as Serabit el-Khadem. This site was also home to a temple of Hathor, the "Mistress of turquoise". A later, two line inscription has also been found at Wadi el-Hol in Central Egypt. Based on hieroglyphic prototypes, but also including entirely new symbols, each sign apparently stood for a consonant rather than a word: the basis of an alphabetic system. It was not until the 12th to 9th centuries, however, that the alphabet took hold and became widely used.

The Cascajal Block, a stone slab with 3,000-year-old proto-writing, was discovered in the Mexican state of Veracruz and is an example of the oldest script in the Western Hemisphere, preceding the oldest Zapotec writing by approximately 500 years. It is thought to be Olmec.

Of several pre-Columbian scripts in Mesoamerica, the one that appears to have been best developed, and the only one to be deciphered, is the Maya script. The earliest inscription identified as Maya dates to the 3rd century BC. Maya writing used logograms complemented by a set of syllabic glyphs, somewhat similar in function to modern Japanese writing.

In 2001, archaeologists discovered that there was a civilization in Central Asia that used writing c. 2000 BC. An excavation near Ashgabat, the capital of Turkmenistan, revealed an inscription on a piece of stone that was used as a stamp seal.

The earliest surviving examples of writing in China—inscriptions on oracle bones, usually tortoise plastrons and ox scapulae which were used for divination—date from around 1200 BC, during the Late Shang period. A small number of bronze inscriptions from the same period have also survived.

In 2003, archaeologists reported discoveries of isolated tortoise-shell carvings dating back to the 7th millennium BC, but whether or not these symbols are related to the characters of the later oracle bone script is disputed.

Over the centuries, three distinct Elamite scripts developed. Proto-Elamite is the oldest known writing system from Iran. In use only briefly (c. 3200 – c. 2900 BC), clay tablets with Proto-Elamite writing have been found at different sites across Iran, with the majority having been excavated at Susa, an ancient city located east of the Tigris and between the Karkheh and Dez Rivers. The Proto-Elamite script is thought to have developed from early cuneiform (proto-cuneiform). The Proto-Elamite script consists of more than 1,000 signs and is thought to be partly logographic.

Linear Elamite is a writing system attested in a few monumental inscriptions in Iran. It was used for a very brief period during the last quarter of the 3rd millennium BC. It is often claimed that Linear Elamite is a syllabic writing system derived from Proto-Elamite, although this cannot be proven since Linear-Elamite has not been deciphered. Several scholars have attempted to decipher the script, most notably Walther Hinz [de] and Piero Meriggi.

The Elamite cuneiform script was used from about 2500 to 331 BC, and was adapted from the Akkadian cuneiform. At any given point within this period, the Elamite cuneiform script consisted of about 130 symbols, and over this entire period only 206 total signs were used. This is far fewer than most other cuneiform scripts.

Cretan hieroglyphs are found on artifacts of Crete (early-to-mid-2nd millennium BC, MM I to MM III, overlapping with Linear A from MM IIA at the earliest). Linear B, the writing system of the Mycenaean Greeks, has been deciphered while Linear A has yet to be deciphered. The sequence and the geographical spread of the three overlapping, but distinct writing systems can be summarized as follows (beginning date refers to first attestations, the assumed origins of all scripts lie further back in the past): Cretan hieroglyphs were used in Crete from c. 1625 to 1500 BC; Linear A was used in the Aegean Islands (Kea, Kythera, Melos, Thera), and the Greek mainland (Laconia) from c. 18th century to 1450 BC; and Linear B was used in Crete (Knossos), and mainland (Pylos, Mycenae, Thebes, Tiryns) from c. 1375 to 1200 BC.

Indus script refers to short strings of symbols associated with the Indus Valley Civilization (which spanned modern-day Pakistan and North India) used between 2600 and 1900 BC. Despite attempts at decipherments and claims, it is as yet undeciphered. The term 'Indus script' is mainly applied to that used in the mature Harappan phase, which perhaps evolved from a few signs found in early Harappa after 3500 BC. The script is written from right to left, and sometimes follows a boustrophedonic style. In 2015, the epigrapher Bryan Wells estimated there were around 694 distinct signs. This is above 400, so scholars accept the script to be logo-syllabic (typically syllabic scripts have about 50–100 signs whereas logographic scripts have a very large number of principal signs). Several scholars maintain that structural analysis indicates an agglutinative language underlies the script.

The Proto-Sinaitic script, in which Proto-Canaanite is believed to have been first written, is attested as far back as the 19th century BC. The Phoenician writing system was adapted from the Proto-Canaanite script sometime before the 14th century BC, which in turn borrowed principles of representing phonetic information from Egyptian hieroglyphs. This writing system was an odd sort of syllabary in which only consonants are represented. This script was adapted by the Greeks, who adapted certain consonantal signs to represent their vowels. The Cumae alphabet, a variant of the early Greek alphabet, gave rise to the Etruscan alphabet and its own descendants, such as the Latin alphabet and Runes. Other descendants from the Greek alphabet include Cyrillic, used to write Bulgarian, Russian and Serbian, among others. The Phoenician system was also adapted into the Aramaic script, from which the Hebrew and the Arabic scripts are descended.

The Tifinagh script (Berber languages) is descended from the Libyco-Berber script, which is assumed to be of Phoenician origin.

In the history of writing, religious texts or writing have played a special role. For example, some religious text compilations have been some of the earliest popular texts, or even the only written texts in some languages, and in some cases are still highly popular around the world. The first books printed widely using the printing press were bibles. Such texts enabled rapid spread and maintenance of societal cohesion, collective identity, motivations, justifications and beliefs that e.g. notably historically supported or enabled large-scale warfare between modern humans.

• Language, Writing and Alphabet: An Interview with Christophe Rico Damqatum 3 (2007)
• "Signs – Books – Networks", virtual exhibition of the German Museum of Books and Writing i.a. with a thematic module on sounds, symbols and script
• Writing Across the Curriculum Clearinghouse – open access books, journals, teaching resources on research and practice.