Most conventions force you to pay a price to use them. For example, when you adopted Takeout Doubles you gave up the ability to make a penalty double of your opponent's opening bid.
Splinter Bids are completely free because they use a DOUBLE jump in a suit, which didn't mean anything
Examples would be:
1♥ - 3♠
1♥ - 4♦
1♠ - 4♥
As you see, these are double-jumps, not to be confused with a Jump-Shift.
The Splinter bid shows 13-16 points, at least 4-card support for Opener's suit, and a singleton or void
in the Splintered suit. The bid absolutely forces the partnership to reach game and sets the trump suit.
There is one admonition - you should not Splinter with a singleton Ace or King, (maybe even Queen). This
is because Opener will be evaluating her hand with the expectation that you have a small singleton, which
is the common case, and will not be expecting any strength from you in that suit.
Splinter Bids can be used after any suit opening, but they are much more frequent after 1 of a Major.
The Convention works very well in conjunction with Jacoby 2NT.
Combined Jacoby 2NT / Splinter Bid lesson available.