In brief
git fetch downloads required objects and updates relevant remote-tracking references. Ordinary fetching alone does not merge the changes into the current working branch.
Useful to know
git fetch downloads required objects and updates relevant remote-tracking references. Ordinary fetching alone does not merge the changes into the current working branch. [1]
This allows histories to be inspected first. An updated origin/main does not prove local main is identical. Receiving data and deciding how to integrate it are separate steps.
Sources
For further detail and to check the information: