Tamil is one of 26 Dravidian Languages spoken on the Indian subcontinent, and is one of the oldest languages not to have been heavily influenced by Sanskrit. Because of this, Tamil is today the closest to that old Dravidian language that existed thousands of years ago ago. In fact, the earliest evidence of Tamil dates back to over 2000 years ago! A fun fact is that the script is so curly because this prevented tears in the palms leaves that were used for paper back in the day.
In India, it is spoken predominantly in the state of Tamil Nadu where it has official status. It is also recognized as an official language in Sri Lanka and Singapore and is a language of education in Malaysia.