This is called as fast-forward merge.
The commits from the child branch are added to the top of the master branch.
This is helpful when we want code from a branch to be reflected as the latest working version on master.
Commit: commit is a meaningful milestone what developer has been achieved.
Rearrange the commit order:
Command: git rebase -i HEAD~4
Merge the commits: using “squash”
Command: git rebase -i HEAD~4 – changing the order
Remove the pick word and replace it with squash.it will hide the commit