What is the purpose of the git merge command and when is it used in working with Git?

The git merge command is used to combine changes from one branch into another. It is typically used when you want to integrate work done in a separate branch back into the main branch (e.g., main or develop).

When executing git merge <branch>, Git attempts to automatically merge the changes from the specified branch into the current branch. If there are no conflicts, a new merge commit is created, combining the histories of both branches.

Example usage:

git checkout main
git merge feature-branch

This will merge the changes from feature-branch into main. If there are conflicts, they need to be resolved manually.

Thus, git merge helps to integrate parallel work and maintain a unified project history.