Before you start building up your application, it's important that you understand what the Common App is and how it works. The Common App, or Common Application, is an application that high schoolers can use to apply to any of the 800+ colleges and universities that accept it. With the Common App, you can apply to schools in the U.S.A, Canada, China, Japan, and many countries in Europe. Here, we'll give you some information about the Common App and what it looks like.