Locations

There are several locations where Git can be configured. From more general to more specific, they are:

• system: /etc/gitconfig, a file that configures Git for all users on the system
• global: ~/.gitconfig, a file that configures Git for all projects of a user
• local: .git/config, a file that configures Git for a specific project
• worktree: .git/config.worktree, a file that configures Git for part of a project

In my experience, 90% of the time you will be using --global to set things like your username and email. The other 9% of the time you will be using --local to set project-specific configurations. The last 1% of the time you might need to futz with system and worktree configurations, but it's extremely rare.

Overriding

If you set a configuration in a more specific location, it will override the same configuration in a more general location. For example, if you set user.name in the local configuration, it will override the user.name set in the global configuration.