It is important to take care of your rubber to maintain its spin characteristics. Without proper care, your rubber can lose a significant amount of spin and even become slick like an anti-spin rubber.
It is recommended that you clean your rubber after each playing session.
A lot of people don't bother with any special cleaning products. Simply using water can do the job fine.
Warning: Some cleaning products contain alcohol and can actually dry out your rubbers, shortening the life of your rubber.
These are sub-pages of the Cleaning Your Rubber page (a child in the hiararchy).