When the person guesses correctly what you have drawn, then it'll be your turn to pay attention to what they're drawing and have a guess at what it is. While you do this, you'll earn coins that you can use to show off to your friends.
The drawing style, as you can imagine, is quite simple. All you have to do is trace your finger on the screen to draw what you want. And don't think you need to be an artist to do this, anyone who can doodle can eventually win the game.
Draw Something Free is one of the most popular apps in the Appstore for a very simple reason: it's easy to draw and it's extremely fun. Anyone can doodle on the screen of their iOS device and playing it with friends makes it really addictive.