Computer basics, in plain English · Updated October 1, 2026
People say “use the app” for everything from checking the weather to writing a letter. What do they mean?
The simple answer
An app is a piece of software that helps you do a task. “App” is short for “application.” On a computer, you may also hear it called a program.
Think of an app as a tool
- A calculator app helps you work with numbers.
- A camera app lets you take pictures.
- A writing app helps you make documents.
- A browser app lets you visit websites.
Your device can have many apps, just as a kitchen has different tools for different jobs.
How do I open one?
Look for its name or picture, called an icon. On a phone or tablet, you usually tap it. On a computer, you can choose it from the app menu, search for its name, or open its desktop icon.
Some desktop icons need a double-click. Items in menus usually need one click.
How do I close one?
Save your work first. Computer apps usually have a close button on the window. A Mac app can stay running after its window closes; its menu’s Quit option closes the app.
On a phone, going back to the home screen leaves the app’s screen. The phone manages what can keep running in the background. You generally do not need to force-close every app after using it.
An app, a file, and an account
These do different jobs:
- App: The tool, such as a photo viewer.
- File: The saved item, such as your dog’s photo.
- Account: Your sign-in with a service, often connected to an email address.
Installing an email app does not automatically create an email account. Removing an app does not necessarily delete your account with its service.
Where do apps come from?
Some arrive with your device. Others come from its official app store or the software maker’s official website. Check the app’s name, maker, and any cost before installing.
If an app asks to use your camera or location, consider whether that fits what you are doing. A video call needs a camera; a simple calculator usually does not.
Try it yourself
Open your device’s calculator. Work out 2 + 2, then leave or close it. You have used an app to do a task.
Next, learn what files and folders are.
Keep learning: What Is a Computer? · More beginner guides
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