SSL Session ID is used to:

A.
Resume old SSL sessions — the keys remain the same

B.
Give loadbalancers the opportunity to loadbalance SSL based upon a non-encrypted field that stays constant throughout one
session, yet is guaranteed to change between sessions

C.
Resume old SSL sessions — the keys are recomputed using the old master_secret and new random values

D.
Allow the client to distinguish between the various SSL connections it has to a server

E.
Allow the server to distinguish between the various SSL connections it has to a client