The most popular bridge convention (i.e. the game of bridge) to find a major suit fit after an opening bid or an overcall in No Trumps, particularly 1NT.
The most popular variation is a 2C response to 1NT asking for a 4-card major. It is important for the responder to have an answer to any response he may receive.
There are variations like Puppet Stayman which enables players to open 2NT with a 5 card major and still find a 5-3 major suit fit.
Using Stayman often promises enough strength to invite to game. But even if that is your understanding with your partner, you can play "Garbage Stayman"