How to set a countdown for a photo?

If I wanted to take a photo of my friends and I without holding the camera how could I do it? Like if I set up the phone standing up and press the button to capture the photo, there will be a countdown so I have time to get in the picture with my friend before the photo is taken. What is this called? And is there an app for iPhone?

Hi! There are plenty of apps, I have some on my iPhone, Just go to the app store and search "picture timer":)

It is called a self timer. Just search the app store for one.