Tense–aspect–mood

Tense–aspect–mood (commonly abbreviated tam) or tense–modality–aspect (abbreviated as tma) is a group of grammatical categories that are important to understanding spoken or written content, and which are marked in different ways by different languages.

TAM covers the expression of three major components of words which lead to or assist in the correct understanding of the speaker's meaning:

• Tense—the position of the state or action in time, that is, whether it is in the past, present or future.
• Aspect—the extension of the state or action in time, that is, whether it is unitary (perfective), continuous (imperfective) or repeated (habitual).
• Mood or modality—the reality of the state or action, that is, whether it is actual (realis), a possibility or a necessity (irrealis).

For example, in English the word "walk" would be used in different ways for the different combinations of TAM:

• Tense: He walked (past), He walks (present), He will walk (future).
• Aspect: He walked (unitary), He was walking (continuous), He used to walk (repeated).
• Mood: I can walk (possibility), Walk faster! (necessity).

In the last example, there is no difference in the articulation of the word, although it is being used in a different way, one for conveying information, the other for instructing.

In some languages, evidentiality (whether evidence exists for the statement, and if so what kind) and mirativity (surprise) may also be included. Therefore, some authors extend this term as tense–aspect–mood–evidentiality (tame in short).