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Installing and removing software on Ubuntu

Understand how software reaches an Ubuntu laptop: package managers, the App Center, snap and deb packages and trusted sources. You will learn how to look at an app before installing it and how to remove it cleanly.

25 minelementaryUbuntu/LinuxPractical task needs a laptop or desktop

Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).

By the end of this lesson you will be able to

  • Explain what a package manager is and why Ubuntu uses one instead of separate installers.
  • Open the App Center and find an app, an installed app and the updates view.
  • Tell a snap package from a deb package at a beginner level.
  • Judge whether an app comes from a trusted source before installing it.
  • Remove an app you no longer need.

On many systems you download a program from a website and double-click it. Ubuntu works differently, and in a safer way. Software comes from organised collections called repositories, delivered by a tool called a package manager. Learning this one idea means you can add useful programs without trawling the web for downloads that might be fake. In this lesson you will look at how that works, practise reading an app's page and learn how to remove what you no longer use.

How software arrives on Ubuntu

Think of a well-run library. You do not wander the streets looking for a book. You ask at the library, which has checked its books, keeps a catalogue and tells you when a new edition is out. Ubuntu works the same way. A repository is an online collection of software prepared and checked for Ubuntu. A package manager is the tool that finds software in the collection, installs it, updates it and removes it.

Software is wrapped in packages. A package contains the program itself and a note of everything else it needs, which is called its dependencies. The package manager reads the note and fetches the missing pieces for you. This is much safer than running an installer from a random web page, because the library has already checked what is on its shelves.

Diagram

How an app gets from an Ubuntu repository to your laptop.

  1. Step 1: ChoosePick an app in the App Center
  2. Step 2: AskPackage manager asks the repository
  3. Step 3: DownloadPackage and dependencies, checked
  4. Step 4: InstallThe app appears in Show Apps
How an app gets from an Ubuntu repository to your laptop.
Read this figure as text

A flow showing the App Center asking a repository for a package, downloading it, installing it and listing it in Show Apps.

Step 1: you choose an app in the App Center. Step 2: the package manager asks an Ubuntu repository for the package and its dependencies. Step 3: the pieces are downloaded and checked. Step 4: the app is installed, and it appears in Show Apps, ready to start. Updates for the app later come through the same route.

The App Center

The App Center is the graphical shop window onto the repositories. On Ubuntu 24.04 it is called App Center. Older releases called it Ubuntu Software, and you may meet that name in guides. Open it from the dock or by pressing Super and typing “App Center”. You will see a way to browse featured apps, a search box, a list of Installed apps and a view for Updates. Exact layout and names can differ between versions.

Simulated interface: not a real screenshot

An illustration of an app's page in the App Center. The app is made up for teaching.

App Center
Explore
Installed
Updates

Notepad Plus (an invented example app)

Publisher: Example Team | Source: Ubuntu repository

Download size: 12 MB | Licence: open source

Install
  1. Marker 1: Explore, Installed and Updates
  2. Marker 2: App name
  3. Marker 3: Publisher and source
  4. Marker 4: Size and licence
  5. Marker 5: Install button
An illustration of an app's page in the App Center. The app is made up for teaching.
Read this figure as text

A simulated App Center page for an invented app called Notepad Plus showing source, size and an Install button.

A simulated App Center window, drawn as an illustration and not a real screenshot. Marker 1 is the sidebar listing Explore, Installed and Updates. Marker 2 is the app name, here an invented app called Notepad Plus. Marker 3 is the line showing the publisher and the source, which is an Ubuntu repository. Marker 4 is the download size and licence. Marker 5 is the Install button. A real page also shows a description and sometimes screenshots.

When you click Install, Ubuntu may ask for your password. This is normal when you have just started an installation, because adding software changes the whole computer and only an administrator may do that. It is not normal if you did not start anything. The password box belongs to your own computer. Never type your password into a web page that asks for it to “install” something.

Snap and deb: two kinds of package

You will often see two words next to an app: snap and deb. You do not have to understand all the details yet, only the difference in idea.

A deb package is the traditional Ubuntu kind. It is installed by a tool called apt, shares ready-made pieces with other programs, and is updated together with the system. A snap package is a newer kind that bundles an app and nearly everything it needs into one self-contained parcel, and runs it in a restricted area. Snaps update themselves in the background and can be a little larger. Ubuntu uses both. For example, the Firefox web browser on recent Ubuntu releases is delivered as a snap. The App Center usually shows where an app comes from, and chooses a sensible default for you.

Diagram

Snap and deb compared in plain terms.

Deb packageTraditional Ubuntu kind
  • Installed by apt
  • Shares pieces with other programs
  • Updated with the system

Small and familiar.

Snap packageSelf-contained parcel
  • App bundled with what it needs
  • Runs in a restricted area
  • Updates itself in the background

Isolated and tidy.

Snap and deb compared in plain terms.
Read this figure as text

A comparison of snap and deb packages: how they are bundled, updated and isolated.

Two columns. Deb package: the traditional Ubuntu package, installed by apt, shares ready-made pieces with other programs so it is usually smaller, and is updated with the rest of the system. Snap package: a self-contained parcel holding the app and what it needs, runs in a restricted area, updates itself in the background and is often a little larger. Ubuntu uses both kinds, and the App Center usually picks a sensible one for you.

Behind the App Center, the apt command and a tool called dpkg do the work for deb packages. You will learn to type apt commands in a later module, once you understand permissions. For now, the App Center does everything you need. Other flavours of Linux use different tools. Fedora, for instance, uses a different package system, and the names of the graphical shops differ. The idea of a trusted collection is the same.

Deciding whether to trust an app

Software from the official Ubuntu repositories and the main App Center has been through some checking. That does not guarantee that every app is perfect, so look at the app's page before you install it. Read the description, see who publishes it, look at its licence, and read the reviews if they exist. Prefer well-known apps with many users over unknown ones that promise too much.

  • Does the page show a sensible publisher and a clear description?
  • Is the app popular and widely used, not brand new with no reviews?
  • Does the app ask for access that makes sense for its job? A note-taking app has no need for your camera.
  • Do you actually need it? Every app you add is something else to keep updated.

Removing an app

Programs you do not use take up space and need updates. In the App Center, open Installed, find the app and choose Uninstall (the word can differ slightly between versions). Ubuntu may ask for your password again, because removing software changes the computer. Your own files, such as documents you created with the app, are not usually removed with it, but it is still good practice to know where they are saved before you remove anything.

Diagram

A short checklist to decide whether to install a program.

  • Do you really need this program?
    • YesIs it in the App Center?
      • YesDo thisRead the publisher, description and licence. If they make sense, install it.
      • NoDoes the maker's official site give clear Ubuntu instructions?
        • YesDo thisAsk someone experienced to check the page with you before you run anything.
        • NoDo thisDo not install it. Look for a different program in the App Center.
    • NoDo thisDo not install it. Fewer programs means fewer updates and fewer risks.
A short checklist to decide whether to install a program.
Read this figure as text

A decision chart with questions about source, need and trust leading to install, wait or avoid.

Start: do you really need this program? If no, do not install it. If yes: is it in the App Center or the official Ubuntu repositories? If yes, read the publisher and description and install if they make sense. If no: does the maker's official website offer it with clear instructions for Ubuntu? If yes, ask someone experienced to check it with you before you run anything. If no, do not install it.

Common mistakes

  • ✖ Instead of: Downloading an installer file from the first search result.

    ✔ Do this: Look in the App Center first. If an app is only on the maker's site, check you have the official address.

  • ✖ Instead of: Removing an app by deleting its dock icon.

    ✔ Do this: That only removes the shortcut. Use Uninstall in the App Center.

  • ✖ Instead of: Installing several apps that do the same thing.

    ✔ Do this: Pick one that is well known. Extra apps cost space and need updates.

  • ✖ Instead of: Typing the password into any box that asks for it.

    ✔ Do this: Only type it if the box appeared right after you started the installation yourself.

If something goes wrong

The App Center cannot find an app I know.
Check the spelling and try a simpler search. It may not exist for Ubuntu, or may be called something else. Search for the type of program instead, such as “video editor”.
The installation seems stuck or fails.
Check you are connected to the internet. Wait a few minutes. Close the App Center and try again. If an update is running, wait for it to finish.
I cannot find the app after installing it.
Open Show Apps and scroll through the alphabetical list, or press Super and type its name. In the App Center, the Installed list also shows it.
The App Center asks for an administrator's approval and I am not one.
A standard user cannot install software for the whole computer. Ask the person who looks after the computer.

Key terms

Package manager
A tool that finds, installs, updates and removes software for you from trusted sources.
Repository
An online store of software or project files that tools can download from.
App Center
The built-in Ubuntu store where you search for, install and remove apps.
Snap package
An Ubuntu software bundle that carries everything the app needs, so it runs the same on different systems.
Deb package
An installable software file used by Ubuntu and other Debian-based Linux systems.
Dependency
Another piece of software that a program needs in order to work.

Practise it for real

Reading is not the same as being able to do it. Complete these on your own computer, then tick only what you have actually done. These ticks are your own honest record: nothing checks them for you.

Guided exerciseNeeds a laptop or desktop

Explore the App Center without installing

Open the App Center. Look at the Installed view and write down three apps you recognise and three you do not. Use the search to find a simple text editor or image viewer. Open its page, but do not click Install. Write down the publisher, the licence and the download size shown.

You have succeeded when:
Independent challengeNeeds a laptop or desktop

Challenge: judge three apps and plan a safe install

Choose three apps in the App Center that do similar jobs, for example three audio players. For each, write down the publisher, the licence and whether it is a snap or deb (the page usually shows the source). Decide which you would install and give two reasons. Then explain how you would remove it again later. You do not have to install anything.

You have succeeded when:

Knowledge check

6 questions. You need 80% to pass. Mistakes here are part of learning, and you can retry as often as you like.

  1. Question 1.What is a package manager?
  2. Question 2.A website offering a “free Ubuntu app” download is as safe as the App Center.
  3. Question 3.Match each description to the package type.
  4. Question 4.Put the steps for installing an app in order.
    1. Click Install
    2. Read the publisher and description
    3. Find the app in Show Apps
    4. Search for the app in the App Center
  5. Question 5.Joseph visits a website, and a box pops up saying “Enter your Ubuntu password to install the missing player”. He did not start any installation.What should he do?
  6. Question 6.Which is the best way to remove an app you installed and no longer need?

Summary

  • Ubuntu installs software through package managers that fetch from repositories.
  • The App Center is the graphical way to find, install, update and remove apps.
  • Snap packages are self-contained; deb packages are the traditional shared kind.
  • Read the publisher, licence and source before installing, and prefer the App Center.
  • Only type your password when a prompt follows something you started yourself.

Checklist: can you do these?

Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).

Related lessons

References and further reading

Official sources for details that can change between versions.

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