NOTRUMP OPENING BIDS -- Part I -- Follow-ups to Stayman

Spelled out here are most of the likely follow-ups to Stayman:

After 2 (Stayman):
Opener answers Stayman and responder's subsequent 2-level bids are not forcing:
1N-2-2-2 is "Garbage Stayman" -- meaning that opener must pass or correct.
1N-2-2-2 is a 5-card spade suit and an off-shape invitational hand (likely 5-4 in the majors).

1N-2-2-2 is multi-purpose. It shows 4 and is presumed to be an invitational hand.

1N-2-2any-2NT is invitational to 3NT and doesn't guarantee a 4-card major (because 1N-2N directly=)

Opener answers Stayman and responder's subsequent 3+ level bids are:
3/3=Weak--To Play--presumably with a major, or would have just transferred. (example: 1NT-2-2-3)
3-of-a-major-raise: Invitational (example: 1NT-2-2-3)
3-of-the-other-major: Artificial Slam-Interest Raise (example: 1NT-2-2-3=Heart raise, slam interest)
Jump to 3-of-a-major after 1NT-2-2: 5-4 in the majors, Game Forcing (but see Smolen)
3NT: To play (with 4 cards in the other major) (example: 1NT-2-2-3NT) note: Opener bids hearts first with 4-4.
 

Opener answers Stayman and responder's subsequent 4+ level bids are:

4 of a new lower ranking suit: Splinter (example: 1NT-2-2-4)
4NT: Quantitative (With at least one major) (example: 1NT-2-2-4NT)

note: This covers 90% of Stayman auctions. Very serious partnerships can delve deeper. If you want to ask for Keycards after Stayman, first bid 3-of-the-other major to set trump, then use RKC.

note: Yes, for experts who play as regular partners week after week, there are more sophisticated methods available.