Cue Bid Raise
A Cue Bid Raise shows a raise of partner's suit when direct raise bids are used to show something other than the specs for a normal raise. This convention is for a single raise. See Cue Bid Limit Raise for a jump raise.
In SAYC, after (1)-1-(1), a raise to
In the Cue Bid Raise Convention,
This gives partner a more precise count on your hand.
More On SAYC Cue Bid
In SAYC, a cue bid is simply a forcing bid which can be used with any good hand for which no better bid is available. It may or may not be a raise. This is clarified by subsequent bidding.
For example in his book, Overcalls, page 145, Mike Lawrence shows J963 AK85 T942 7 and bidding of 1D-1S-2C, and says to cue bid 2D, despite having only 8 HCPs.
Since on the bidding, and assuming nobody has lied, advancer can hardly have an 11+ HCP hand, so the cue bid cannot normally be a general strength-showing bid, but must be a strong raise based primarily on shape and support.