Checkout Checkback Stayman

Checkback Stayman is a bridge bidding convention used by the responder to find a major-suit fit after the opener rebids 1NT (showing 12–14 HCP) or 2NT (showing 18–19 HCP). 

It "checks back" for a 5-3 fit in the responder's major or a 4-4 fit in an unbid major that the opener might have bypassed.

Watch this YouTube video (created with AI) that explains the convention and how it can hone your game...