Tolkāppiyam is an old book from South India that helps people learn how to write and speak Tamil language. It teaches us about the sounds, rules and structure of Tamil language. Imagine Tamil language is like a game with lots of rules, and Tolkāppiyam teaches you all these rules so that you can play the game perfectly. It's like learning how to build Lego blocks - each block needs to fit in the right place in order to make a perfect structure, and Tolkāppiyam teaches you how to fit the Tamil 'blocks' perfectly.