An application program is software you run on your device to do a specific job

An application program (or app) is a piece of software built to perform one or more tasks for you. Unlike the operating system that runs your device in the background, an application does something visible: it lets you write a document, send an email, edit a photo, play music, or check your bank balance. The application sits on top of your operating system and uses it to talk to your hardware.

When you open Microsoft Word, you are running an application program. When you tap Instagram on your phone, you are running an application program. When you launch Spotify to listen to music, that is an application program too. Each one was written by a company or developer to solve a specific problem or let you do a specific thing.

The key difference between an application and your operating system is purpose. Your operating system (Windows, macOS, iOS, Android) manages your device itself — it controls the hard drive, the screen, the keyboard, the network connection. An application uses those tools to let you accomplish something. You do not think about the operating system when you are working; you think about the application.

Key Takeaways

  • An application program is software designed to perform a specific task, like writing documents, sending emails, or editing photos.
  • Applications run on top of your operating system and rely on it to communicate with your device's hardware.
  • Desktop applications (like Microsoft Word) and mobile apps (like Instagram) are both application programs, just built for different devices.
  • You can install multiple applications on one device, and each one works independently while sharing the same operating system.
  • Web applications run inside your browser instead of being installed on your device, but they work the same way from your perspective.

How an application program talks to your device

An application cannot directly control your hardware. Instead, it sends requests to your operating system, which then handles the actual work. When you click the print button in a document, the application does not print directly — it tells the operating system "print this," and the operating system sends the job to your printer.

This arrangement protects your device. If every application could access your hard drive or network directly, a malicious program could steal your files or send your data somewhere without your permission. By forcing all applications to go through the operating system, your device can check what each application is trying to do and block anything dangerous.

This is also why an application written for Windows will not run on a Mac, and an app written for iPhone will not run on Android. Each operating system has its own language for talking to hardware. An application has to be written in that language, or translated into it, to work on that device.

The difference between desktop applications and mobile apps

A desktop application is software you install on a computer — Windows, Mac, or Linux. Examples include Microsoft Office, Adobe Photoshop, Google Chrome, and Slack. You download an installer file, run it, and the application lives on your hard drive. When you want to use it, you click an icon or search for it by name.

A mobile app is software you install on a phone or tablet. You find it in the App Store (Apple) or Google Play (Android), tap "Install," and it downloads to your device. The app then appears on your home screen or in your app drawer. Mobile apps are built differently from desktop applications because phones and tablets have smaller screens, touch controls instead of a mouse, and less processing power.

Despite these differences, both are application programs doing the same thing: running on top of an operating system to let you accomplish a task. A mobile app for banking works the same way as desktop banking software — it just looks different and is designed for a smaller screen.

Web applications and cloud-based software

A web application is software that runs inside your web browser instead of being installed on your device. Gmail, Google Docs, Canva, and Figma are all web applications. You do not download or install anything — you go to a website, log in, and start using it. The software itself lives on a company's servers, not on your computer.

From your perspective, a web application works like any other application: you open it, use it to do something, and close it. The difference is that all the heavy lifting happens on distant servers, and your browser just displays the results. This means you can use the same web application on any device with a browser — your laptop, phone, or tablet — without installing anything.

Web applications have become more common because they do not require installation, they update automatically, and you can access your work from anywhere. The trade-off is that you need an internet connection to use them, whereas a desktop application or mobile app can often work offline.

How applications get on your device

For desktop computers, you usually download an installer file from the company's website or from a software store like the Microsoft Store. You run the installer, it unpacks the application files onto your hard drive, and the application is ready to use. Some applications require a license key or subscription to run.

For phones and tablets, you open the App Store or Google Play, search for the application, and tap the install button. The store handles downloading and installing it for you. Most mobile apps are free, though some cost money upfront or charge a subscription.

For web applications, there is nothing to install. You simply visit the website in your browser. Some web applications require you to create an account and log in; others let you use them without signing up.

Why you have multiple applications on one device

Your operating system is designed to run many applications at the same time, each one doing its own job. You might have Microsoft Word open for writing, Slack open for messaging, and Chrome open for browsing — all running at once. The operating system divides your device's processing power and memory among them so they can all work without interfering with each other.

Each application is independent. Closing Word does not affect Slack. Uninstalling Slack does not affect your other applications. They share the same operating system and hardware, but they do not depend on each other to function.

This is different from the operating system itself. If your operating system crashes, all your applications stop working because they have no foundation to run on. But if one application crashes, the others keep running, and you can restart just that one application.

Common types of application programs

Productivity applications help you create and organize information: word processors (Microsoft Word), spreadsheets (Excel), presentation software (PowerPoint), and note-taking apps (OneNote, Notion).

Communication applications let you connect with other people: email clients (Outlook, Gmail), messaging apps (WhatsApp, Slack), and video calling software (Zoom, Teams).

Creative applications are for making visual or audio content: photo editors (Photoshop, GIMP), video editors (Adobe Premiere, DaVinci Resolve), and music production software (Ableton, GarageBand).

Utility applications perform specific technical tasks: file managers (Windows Explorer, Finder), antivirus software, backup tools, and system cleaners.

Entertainment applications are for consuming or creating media: streaming services (Netflix, Spotify), games, and social media apps (Instagram, TikTok).

Most devices come with a few built-in applications (like a calculator or calendar), but you install additional applications based on what you need to do.

Frequently Asked Questions

Is an application the same thing as a program?

Yes, in everyday language "application" and "program" mean the same thing. Technically, a program is any software, while an application is a program designed for end users to accomplish a task. But most people use the terms interchangeably.

Can I run the same application on my computer and my phone?

Not always. An application written for Windows will not run on an iPhone, and vice versa. However, many companies release versions of the same application for different operating systems — for example, Microsoft Office exists for Windows, Mac, and iPad. These are technically different applications, but they look and work the same way.

What happens if I uninstall an application?

The application is removed from your device, and you lose access to it. Your other applications and your operating system are not affected. If you change your mind, you can reinstall it later. Any files you created with that application remain on your device unless you delete them.

Do I need to pay for every application I use?

No. Many applications are free, including Microsoft Word (online version), Google Docs, Slack (basic version), and most social media apps. Some applications cost money upfront, and others are free but charge a monthly or yearly subscription for advanced features.

Why does my device slow down when I have many applications open?

Each open application uses some of your device's memory and processing power. If you open too many at once, your device runs out of resources and everything slows down. Closing applications you are not using frees up that memory and speeds things back up.