What is msi?
MSI stands for Microsoft Installer. It is a file format (with the .msi extension) that Windows uses to package software so it can be installed, repaired, updated, or removed in a consistent way.
Let's break it down
An MSI package is like a small database. Inside it you’ll find tables that list all the files to copy, the registry changes to make, shortcuts to create, and the steps (called actions) the installer should follow. When you run the MSI, Windows reads this database and carries out the instructions automatically.
Why does it matter?
Because MSI gives developers a standard way to deliver software, users get a predictable install experience. It also lets Windows keep track of what was installed, so you can easily repair a broken program or cleanly uninstall it later.
Where is it used?
- Most Windows desktop applications you download from the internet.
- Corporate environments that push software to many computers at once.
- Windows Update and other system components that need to add or modify files safely.
Good things about it
- Consistent install/uninstall experience for users.
- Supports silent (no‑UI) installations, useful for automated deployments.
- Allows repair and patching without reinstalling the whole program.
- Keeps a record in the system so you can see what’s installed and remove it cleanly.
Not-so-good things
- MSI files can be large and sometimes include unnecessary components.
- Creating a well‑structured MSI can be complex for developers; it often requires special tools.
- Some older or niche programs still use custom installers that don’t follow MSI standards, leading to inconsistencies.
- If the MSI database gets corrupted, the program may become difficult to repair or uninstall.