Quick answer
Quick answer: If you touch one of your pieces meaning to move it, you must move it. If you touch an opponent's piece, you must capture it. If it has no legal move, nothing happens and you play on.
The move itself is finished the moment you let go of the piece on a square.
You can adjust a piece without moving it, but you have to say so first, before you touch it.
The rule only applies over the board. Online, the software decides everything and touch move doesn't exist.
What the law actually says
It's worth reading the real wording, because the summaries drift.
The FIDE Laws of Chess say a player who touches a piece with the intention of moving it must move the first piece touched that can be moved.
Touch an opponent's piece and you must capture the first piece touched that can be captured.
There's also a line people forget. Each move must be played with one hand only, so you can't castle with two hands or hold a piece down while you think.
I read the article in full rather than quoting a forum summary, because the intention clause is the part that gets dropped.
Intention is part of the rule
This is the get out clause, and it's narrower than people hope.
The rule applies when you touch a piece with the intention of moving it. Brushing a piece with your sleeve is not an intention.
Knocking a piece over while reaching for your clock is not an intention either.
What it does not cover is changing your mind. Picking up your knight, seeing the refutation and putting it back is exactly what the rule exists to stop.
In practice an arbiter decides, and arbiters are experienced at telling an accident from a regret.
Say it before you touch it
The adjustment rule, and the order matters more than the words.
You may straighten a piece on its square by first saying j'adoube, or simply I adjust, and then touching it.
Say it afterwards and it counts for nothing. The announcement has to come first.
You can only do this on your own move, and only to tidy pieces, never to test how a move would look.
It's a small courtesy that stops a genuine problem, and it's the single most useful phrase a new tournament player can learn.
When you let go, it is done
The other half of the rule, and the half that costs games.
Once a piece is released on a square as a legal move, it cannot be moved anywhere else on that move.
Not when you press the clock. When your fingers leave the piece.
So the hand hovering over a square is still yours to change. The hand that lifts away is not.
Plenty of players discover this the hard way, letting go, seeing the reply and reaching back. There's nothing to reach for.
Castling and the touch rule
Castling has its own line because it involves two pieces.
Touch the king and the rook and you must castle, provided castling is legal.
If castling isn't legal at that moment, the touch is treated as touching the king, so the king must move if it legally can.
That's why the rule of thumb is to move the king first and always with one hand.
Our castling guide covers when castling is illegal in the first place, which is the more common confusion.
Promotion counts as a touch too
A detail that catches out even experienced players.
When you promote, the choice of piece is finalised the moment that piece touches the promotion square.
So reaching for a queen, touching it down and then wanting a knight instead is too late.
Decide before your hand moves, not while it's moving.
That matters more than it sounds, because a knight is occasionally the winning choice and the queen is the reflex.
If the piece cannot move
The escape hatch nobody explains properly.
If you touch a piece that has no legal move at all, nothing happens. You simply play something else.
A pinned piece is the usual case. Touch a knight that's absolutely pinned to your king and there is no penalty, because it had no legal move to make.
The same is true for an opponent's piece that cannot legally be captured.
I checked that against the wording of the law before writing it down, because it is the exception most club players get wrong in both directions. So the rule never forces an illegal move. It only forces a legal one you regret.
What if you make an illegal move?
A separate rule, and worth knowing before your first event.
An illegal move counts as completed once you press your clock. The position goes back to before the mistake.
For a first illegal move, the arbiter gives your opponent two extra minutes. A second illegal move in the same game loses it.
So one slip is survivable and two are not.
Note that this is separate from touch move. You can break both in one motion, and each carries its own consequence.
Online chess has no touch move
Because it can't, and this shapes how people play.
A mouse hover isn't a touch, a drag can be released back where it started, and premoves make the whole idea meaningless.
The rules of chess as written assume a physical board, and a server enforces its own version of legality instead.
That's why the first over the board game feels so different for an online player.
You lose the ability to try a move visually, and that habit is exactly what touch move punishes.
How to stop it costing you
Three habits, and the first is the whole answer.
Decide, then reach. Not reach, then decide. Your hand should only move when the move is already chosen.
Keep your hands in your lap or on the table edge while you think, so nothing is hovering.
And do your final safety check before you touch anything, not while your fingers are on the piece.
Our blunder check routine is built to run before the hand moves, which is exactly the discipline touch move demands.
Casual games and club nights
Where it gets social rather than legal.
In a friendly game, most people don't enforce it, and insisting on it against a beginner makes you unpleasant company.
In a rated club game, it's enforced and expected, and letting your opponent take a move back is a favour, not a right.
The sensible approach is to agree before you start if there's any doubt.
One sentence at the beginning prevents an argument in the middle, and the argument is always worse than the position.
The famous incidents
Worth knowing that this bites at every level.
Grandmasters have lost games to it, and the pattern is always the same. A player touches a piece, sees the problem a second later, and has to play the move anyway.
It isn't a beginner's rule. It's a rule that catches anybody who reaches while still calculating.
Which is a useful thing to know, because it means the habit is worth building deliberately.
You can practise it against a bot on the board by simply refusing to take moves back, even when nothing stops you.
Rapid, blitz and the clock
The rule survives at every speed, and gets harder to obey.
Blitz is where touch move causes the most disputes, because everything happens too fast for a clean memory of who touched what.
Events often run with an arbiter watching precisely for that reason.
The practical advice at speed is the same as at slow play. One hand, no hovering, and press the clock with the hand you moved with.
Our time control guide covers what to expect at each speed.
The short version
Touch your own piece meaning to move it and you must move it.
Touch an opponent's piece and you must capture it, if a legal capture exists.
Say j'adoube before you touch, never after, and only on your own move.
Releasing a piece on a legal square ends the move immediately, before the clock.
And none of this exists online, which is exactly why online players get caught by it in their first tournament.