Pigs are animals that can be livestock in Stardew Valley. They can be purchased at Marnie's Ranch for 16000g and are unlocked with the Deluxe Barn, making them the most expensive animal in the game.
Pigs can find Truffles, which, using an Oil Maker, can be made into Truffle Oil. This Artisan Good, in turn, is used in recipes and a bundle at the Community Center.