A software application is a program you run on your device to do a specific task
A software application — or app — is a set of instructions written in code that tells your device to perform one or more jobs. When you open it, the program runs those instructions in order. The app stays open until you close it or it crashes. Examples include email programs like Outlook, web browsers like Chrome, photo editors like Photoshop, games, calculators, and word processors like Microsoft Word.
The key difference between an app and other software is focus. An app does one main thing well: email, photo editing, note-taking, video calls. Other software — like operating systems or drivers — runs in the background and manages how your device works overall. You do not usually open them directly.
Apps exist on every device: phones, tablets, computers, and even smart TVs. The app you use on your phone to check email is different code than the email app on your computer, even though they do the same job. Each one is written for its own device type.
Key Takeaways
- A software application is a program designed to do one specific task, like send email, edit photos, or play music.
- Apps run on your device only when you open them, unlike operating systems or drivers that work in the background all the time.
- The same app name on your phone and computer is actually two different programs written for two different device types.
- Apps can be free or paid, and they come from app stores, websites, or are pre-installed on your device.
How an app differs from an operating system
Your device's operating system — Windows, macOS, iOS, or Android — is the master software that runs everything. It manages your files, your hardware like your printer and camera, and how programs talk to each other. You do not open the operating system the way you open an app. It runs automatically when you turn on your device and keeps running until you shut down.
An app, by contrast, only runs when you choose to open it. It relies on the operating system to do the heavy lifting — to find files, send data to your printer, or connect to the internet. The app is a passenger; the operating system is the driver.
Think of it this way: the operating system is the engine and steering wheel of a car. An app is a specific tool you pull out of the trunk — a jack, a flashlight, a first aid kit. Each tool does one job. The car runs whether you use the tools or not.
Where apps come from and how you get them
Most apps today come from app stores. On iPhones and iPads, that is the Apple App Store. On Android phones, it is Google Play. On Windows computers, it is the Microsoft Store. Each store checks apps before they are listed there, though the level of checking varies.
You can also download apps directly from a company's website. Microsoft Office, for example, can be downloaded straight from Microsoft's site. Some software — especially older programs or specialized tools — only comes this way.
Many devices come with apps already installed. Your phone probably has a camera app, a calculator, and a maps app built in. Your computer likely came with a web browser and a file manager. You can usually delete these if you do not want them, though some are tied to the operating system and cannot be removed.
Free apps versus paid apps
Free apps do not cost money to download or use, but they make money in other ways. Some show advertisements while you use them. Others collect data about you — what you search for, where you go, what you buy — and sell that information to advertisers. Some free apps offer a basic version for free and charge money for extra features (called a "freemium" model).
Paid apps cost money upfront, usually between one dollar and fifty dollars, though some specialized software costs much more. Once you pay, you own a license to use the app. You do not own the code itself — the company does — but you own the right to run it on your device. Paid apps typically do not show ads or collect data the way free apps do, though some do both.
A third option is a subscription app. You pay a monthly or yearly fee to keep using it. Microsoft Office 365, Adobe Creative Cloud, and many streaming services work this way. When you stop paying, you lose access.
What happens when you open an app
When you click or tap an app icon, your device loads the app's code from storage into memory — the fast, temporary space where your device runs active programs. The operating system gives the app access to what it needs: your screen, your keyboard or touchscreen, your internet connection, your files.
The app then displays its interface — the buttons, menus, text boxes, and images you see on screen. Everything you do in the app — typing, clicking, swiping — sends signals back to the code, which processes them and updates what you see.
When you close the app, the operating system removes it from memory and stops running its code. If you were working on something unsaved, it is usually lost (though many apps save your work automatically). The app stays on your device's storage until you delete it.
Why apps crash and what that means
An app crashes when its code encounters an error it cannot fix. This might happen because the code has a bug, because the app ran out of memory, because your device lost internet connection at the wrong moment, or because the app is not compatible with your device's operating system version.
When an app crashes, it closes suddenly without warning. You lose any unsaved work. Your device usually offers to send an error report to the company that made the app, which helps them find and fix the bug in the next update.
Crashing is different from freezing. A frozen app stops responding to your clicks or taps but stays open. You can usually force it closed by using your device's task manager (on Windows) or by swiping it away (on phones). A crash closes the app for you.
How apps get updated and why
App makers release updates to fix bugs, add new features, improve speed, or patch security holes. On phones, updates usually happen automatically if you have automatic updates turned on. On computers, you may see a notification that an update is ready, or you may have to check manually in the app store.
Updates are important for security. If someone discovers a way to hack into an app, the company releases an update to close that hole. If you do not update, your device and your data become more vulnerable.
Updates can also change how an app looks or works. Sometimes people dislike a new update because the interface changed or a feature moved. You cannot usually go back to an older version once you update, though some apps let you downgrade if you uninstall and reinstall an older version from a backup.
Frequently Asked Questions
Is there a difference between an app and a program?
Not really. "App" is short for application, and "program" means the same thing. "App" became common when smartphones arrived and people started calling phone software "apps" to distinguish them from computer software. Today the words are used interchangeably.
Can I use the same app on my phone and my computer?
Not the same copy. The code is different because phones and computers work differently. However, many companies make versions of the same app for both devices — like Gmail, Slack, or Spotify. Your account and data sync between them, but you are running two separate programs.
What does it mean when an app asks for permission?
When you first open an app, it may ask permission to access your camera, microphone, location, contacts, or files. This is a security feature. The app cannot use these things without your permission. You can change these permissions later in your device's settings.
Why does an app take up storage space even when I am not using it?
The app's code, images, and data are stored on your device's hard drive or solid-state drive. They stay there until you delete the app. Larger apps — like games or video editors — can take up gigabytes of space. You can delete apps you no longer use to free up space.
Can I use an app without internet?
Some apps work offline, like calculators, note-taking apps, or games that do not need to connect to servers. Others need internet to function — email apps, social media, streaming services, and online games. Many apps work partly offline and partly online, like maps that cache downloaded areas.