1.Use git push origin(remote) more-speech(branch) to push the latest branch to a remote.
2.Here we use git merge to merge two branch together. We have to enter the target branch and run git merge branch_we_want_to_use.
3.A branch can be think as a collection of commits.
4.Use git branch -d branch_name to delete unnecessary branch. The branch can be deleted after it is merged to another branch.
5.We use git fetch to fetch all the repo from remote(origin) to local.
6.Use git diff old_branch new_branch to check the difference between old branch and new branch.
