Much of Tamil grammar is extensively described in the oldest available 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.
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, which would require several words or a sentence in English. To give an example, the word pōkamuṭiyātavarkaḷukkāka (போகமுடியாதவர்களுக்காக) means "for the sake of those who cannot go", and consists of the following morphemes: