In the past, you would simply put a price on your game and then wait for people to purchase it at a store. But today you have options. You can choose to distribute a game to "brick-and-mortar" stores, sell the game online (either physical or soft copies), or let everyone play the game for free but incorporate some sort of ads or in-game items that can be purchased. Games are also no longer just standalone products. They often come with extra content that can be purchased in addition to the main game.