Default apps control which program opens a given file type or protocol, preventing surprises when launching documents, media, or links from email and chat. Keeping these associations consistent reduces friction in daily work and avoids accidentally opening sensitive files in the wrong tool.
In Windows 11, defaults are stored as per-type associations for file extensions (like .pdf) and link/protocol handlers (like mailto or https). The Settings app exposes these mappings through the Default apps page, where each type can be assigned to an installed application that declares support for it.
Some formats require separate changes for closely related extensions (for example .htm and .html), and managed devices may enforce defaults via policy. If the desired application is not installed, Windows may offer a Microsoft Store suggestion instead of applying the change.
Methods to change default apps in Windows 11:
The Settings method sets the system default for a specific file extension or protocol.
Use .pdf or mailto to jump directly to the matching association.
Repeat the same assignment for related extensions to keep similar formats opening in the same application.
The context menu method changes the default for the file type of a specific file.
Changing the default this way applies to the selected file type only.