An app is a computer program designed to help you do specific tasks on a device like a smartphone, tablet, or computer. The word is short for “application,” which is what people called these programs before smartphones made them popular.

Apps do all sorts of things. Some apps help you communicate, like texting or video chat apps. Others let you play games, edit photos, check the weather, learn new skills, or listen to music. There are apps for drawing, reading books, tracking your allowance, and even identifying stars in the night sky.

What makes apps different from regular computer programs is that they're usually simpler and focused on doing one thing well. Instead of complicated software that does everything, you might have separate apps for email, calendars, and notes. Apps are also designed to be easy to find, download, and start using right away, usually from an app store.

When someone says “there's an app for that,” they mean that almost any task or interest you can think of probably has a dedicated app designed to help. The word has become so common that people now talk about having their “favorite apps,” just like they might have favorite books or games.