Walsh is a convention used in the card game of bridge in response to an opening bid of 1♣.
When the values to force to game are held, the procedure is abandoned, and suits are bid in the normal order.
The main purpose of the convention is to avoid missing major suit fits when opener has something akin to a weak notrump, and would rebid 1NT over the normal 1♦ response.
The major suit fit is likely to provide a safer resting place when the hands are weak, as well as potentially scoring better (a concern perhaps only at matchpoints).
It is a form of Canapé and thus the responses of 1♥ and 1♠ to a 1♣ opener are alertable in the UK under EBU regulations.