Template:Media
This template adds an image to the category "{{{1}}} media files", or if that does not exist then "{{{1}}} images", otherwise "{{{1}}} media", with the {{PAGENAME}} sort key.
Tracking category
Category:Pages using Template:Media with ambiguous media category contains pages using this template with an ambiguous category name ending in just "media" rather than "media files" (as opposed to mass media).