Here's how to use Houseparty, the live video app that teens are going crazy for

Anyone who spent a lot of time online in the early 2000s will remember whiling away the hours popping in and out of chatrooms and instant messaging their friends.

But in the years since AIM faded into obscurity, nothing has really replaced instant communication for teens. While Snapchat came close, Generation Z - the cohort born between the mid-1990s and early 2000s - has moved on to another app: Houseparty.

Houseparty is a mobile app for live video chatting. Unlike Facetime or Skype, you can have up to eight people in a room and have several "parties" going at once. It's like a video version of a chatroom, and teens are going crazy for it: the app launched last February and now has more than 1 million daily active users. The app is the 18th most popular app in the App Store and the third most popular social networking app.

Here's how to use it.