Installation (computer programs)

Installation means to put a program on a computer so that the computer can run it.

Most programs are stored in special ways to make them smaller, or to gather all the different pieces of a program up into one big piece. Before it can be used, though, the program needs to have these changes undone. Some programs also need to know extra information about the computer it is going to run on, so while it is installing, it will figure out what it needs to know and write it down for later.^[1]

When an user installs a computer program, the setup usually follows a few steps:

• 1. Checking system requirements

The installer checks if the computer has the right hardware and software: it might need a certain version of the operating system, enough free memory, or a fast enough processor.

• 2. Installing Dependencies

Some apps rely on additional components such as frameworks, libraries or third-party software. If they are not installed, the setup will prompt the users to install them.

• 3. Copying files

The program’s files are copied from the installation source to the computer’s hard drive. These files are typically stored in a specific folder, often under "Program Files" or a similar directory.

• 4. Setting up shortcuts

The installer can create shortcuts on the desktop or in the Start menu. A user can open the program more easily thanks to the shortcuts.

• 5. Changing system settings

Some programs change settings on the computer. For example, they may add new drivers, update environment variables, or register files so that they open with the new program.

• 6. Finalizing and cleaning up

The installer finishes the setup and may offer to start the program right away. It may also delete temporary files used during the process to save space.

Installers come in different formats, each designed for a specific way of installing software on a Microsoft Windows computer.^[2] Here are the most common types:

• MSI (Microsoft Installer)

MSI is the standard format for installing software on Windows. Its technology is based on the Windows Installer system to handle installation, updates, and uninstallation. Its installation structure includes files, registry keys and installation instructions. MSI installers are preferred for application package distribution in enterprise environments.

• EXE (Executable) Setup Files

EXE setup files are one of the most common ways to install software. The .exe file extension is short for “executable”. An EXE offers a user-friendly installation interface and gives developers complete control over the software configuration process, so it allows many custom options. Because of this, they can be harder to manage in large organizations, for which the MSI installer type can be a better solution.

• MSIX

MSIX is the newest format from Microsoft, presented as an improved version of the AppX package and designed as an alternative to both MSI and EXE installers. An MSIX is a zip-based installer that contains your application files and XML configuration files. It offers a more secure and modern way to package and install Windows apps. MSIX files support automatic updates, simpler uninstallation, and better security. They also work well with Microsoft Store apps, where they don't need a signing certificate (they get signed on approval).

On Microsoft Windows computers, many programs use the Windows Installer technology to make installation easier. Windows Installer helps manage the program setup, updating, and removal (uninstall).

To create program installers, developers often use specific tools and softwares. These tools can be grouped into two main types:

These tools require buying a license. They often include advanced features and post-purchase support, needed when building installers for complex software. Popular examples include:

• InstallShield — one of the oldest and most widely used installer builders by the enterprise businesses.

• Advanced Installer — an old tool with an easy user interface, praised client support, and strong adoption for newer Windows technologies like MSIX.

• InstallAware - versatile software with good customization options, able to handle complex installations.

These tools can be used without paying. They are popular with individual developers, open-source projects, and smaller companies. Examples include:

• WiX Toolset — a free, open-source project that uses XML files to create installer packages; it is often used for complex and professional installations.

• InnoSetup — a free tool for creating simple Windows installers.

• NSIS (Nullsoft Scriptable Install System) — open-source, good when needing customization through scripting.

• Wise Installer — an older tool that was once very popular, now discontinued.

Each type of tool helps software developers create installation packages of different levels of complexity, suitable for users to install, update, and remove.

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