Tense–aspect–mood (commonly abbreviated tam in linguistics) or tense–modality–aspect (abbreviated as tma) is an important group of grammatical categories, 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:

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

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).

It is often difficult to untangle these features of a language. Several features (or categories) may be conveyed by a single grammatical construction (for instance, English -s is used for the third person singular present). However, this system may not be complete in that not all possible combinations may have an available construction. On the other hand, the same category may be expressed with multiple constructions. In other cases, there may not be delineated categories of tense and mood, or aspect and mood.

For instance, many Indo-European languages do not clearly distinguish tense from aspect.

In some languages, such as Spanish and Modern Greek, the imperfective aspect is fused with the past tense in a form traditionally called the imperfect. Other languages with distinct past imperfectives include Latin and Persian.