As of 2016 , Facebook has over 1.59 billion active users worldwide. In the US alone, 71% of teens use Facebook.

As of 2015, an estimated 33% of all American teens use Twitter.

Teen usage of Instagram has gone up. As of 2016, 66% of American teenagers and young adults aged 12-24 use the app.

Tinder is the most famous or 'infamous' app used by young adults and underage teens for dating and casual hook-ups. There are an estimated 3 million 13-17 year olds on Tinder.

Snapchat is used by 41% of teens to share images and messages that disappear after the receiver reads and closes the chat screen.

Yik Yak is a social media app that lets users post anonymous messages within a given area. Yik Yak has been criticized for encouraging cyberbullying and has been called "The Wild, Wild West of social apps." The app is in use in more than 22,300 high schools across the US.

Kik is used by an estimated 40% of US teens. Called "the bane of law enforcement", Kik allows users to use pseudonyms and anonymous messages. The app gained notoriety in February 2016 following the death of a 13-year-old Virginia girl who was stabbed to death by an 18-year-old she met on Kik.

This social networking app, called the "anti-Facebook", lets users send anonymous "whispers" - secrets, confessions, innermost thoughts - like a digital diary. Used by teens as a dating app or as venue for cyberbullying. Many confessions are of a sexual nature.

Ask.fm is a question-and-answer app with some 57 million users where teens and tweens ask serious and not-so-serious anonymous questions. Photos, messages, and videos can be exchanged among users.

WhatsApp is a totally free SMS service popular among children and teens that lets users share videos and photos through the Internet. It was purchased by Facebook for $22 billion in 2014.