For questions about visual representation of music and its uses. If the question is about a specific type of notation like tablature, that should also be tagged. Questions about how to input specific notation are best served with the engraving tag.
Notation is the visual representation of auditory phenomena, often for a musician's benefit. Music can be represented in many ways, some of which emphasize higher-level structure and facilitate analysis, while other methods simply instruct a performer on how to perform a piece. One common method, sheet music, indicates the pitches to be sounded by their position on a staff, and their durations via abstract symbols.
See also the discussion at What is the relationship between the notation and engraving tags?