CRR , Reverse Repo rate Repo Rate

Cash reserve Ratio (CRR) :
It is the amount of funds that the banks have to keep with RBI(for bad days as security ). If RBI decides to increase the percent of this, the available amount with the banks comes down. RBI is using this method (increase of CRR rate), to drain out the excessive money from the banks.
Repo Rate : Rate of Interest which RBI charges form other bank if they Borrow any money from RBI.