Facebook is a great way to connect with friends and family faster to see how they are doing and what's going on in their life since you can't be near them.
Snapchat is a fun way to show your friends what your doing now. All you have to do is press the center and start recording what you doing, what you eating, even where your going.
Instagram is just you posting pictures and liking your friends post by just double clicking to the heart heart appear. It just something simple to show your friends anything.
This is just something for famous people I really think. But you just say what you want, and people can retweet or like what you say.