Tamil employs agglutinative grammar, where suffixes are used to mark noun class, number, and case, verb tense and other grammatical categories. Tamil's standard metalinguistic terminology and scholarly vocabularly is itself Tamil, as opposed to the Sanskrit that is standard for most other Dravidian languages.
Much of Tamil grammar is extensively described in the oldest known grammar book for Tamil, the Tolkāppiyam. Modern Tamil writing is largely based on the 13th century grammar Naṉṉūl which restated and clarified the rules of the Tolkāppiyam, with some modifications. Traditional Tamil grammar consists of five parts, namely eḻuttu, col, poruḷ, yāppu, aṇi. Of these, the last two are mostly applied in poetry.
Tamil words consist of a lexical root to which one or more affixes are attached. Most Tamil affixes are suffixes. Tamil suffixes can be derivational suffixes, which either change the part of speech of the word or its meaning, or inflectional suffixes, which mark categories such as person, number, mood, tense, etc. There is no absolute limit on the length and extent of agglutination, which can lead to long words with a large number of suffixes.