What is the function of RDS button in Car Audio system?

[BabulalPrasath]

I bought a 2002 Lexus ES300 recently. I could not figure out what is the function of the RDS button in the Audio system. The owners manual does not speak about this button as there is a different button mentioned there (I think its AF). I read it somewhere RDS stands for Radio Data System. But I need more information on what it does and how to use it?

Also, Not sure of the TYPE button in the audio system.

Could anyone help me in this regard?

Thanks
Babulalprasath