ABSTRACT
Tense, aspect and modality are grammatical categories mainly affecting the verbal constituent of a clause, although adverbials may also contribute to their expression. Tense expresses the temporal location of the situation being talked about, indicating whether this is before, at, or after a particular reference point. In Turkish the primary tense differentiation is between past and non-past. The suffixes involved in the expression of present and future tense are markers of relative tense. Aspect is that part of the grammar of a language which expresses the temporal viewpoint from which a situation is presented. It may be viewed 'from the outside', as a completed whole, with both its starting point and its endpoint visible. Unlike tense and aspect, modality is not related to the concept of time. It is concerned with whether a situation is presented as a directly known fact, or in some other way.
