Create a branch based on the current branch

git checkout -b "new-branch-name"

Create a branch based on the hash value or relative to the latest commit of the current branch

git checkout -b "new-branch-name" <sha1-of-commit or HEAD~3>

How to reset or revert a file to a specific revision?

git checkout c5f567 -- file1/to/restore file2/to/restore

Hard reset of a single file

git checkout -- file-name-that-you-deleted

-- basically means: treat every argument after -- as a file name. More details, please refer to this link.

Add a contributor's remote:

$ git remote add [REFERENCE_NAME] [email protected]:[CONTRIBUTOR_USERNAME]/[REPOSITORY].github.io.git

REFERENCE_NAME is usually a contributor's name, e.g. aaron, mild.

Then, fetch all branches of a contributor's remote.

$ git fetch [REFERENCE_NAME]

Git will suggest a local branch and a tracking remote branch that you can checkout later without -b option which you can't do in other cases"

* [new branch] branch-name -> [REFERENCE_NAME]/branch-name

You can now checkout a new branch with:

$ git checkout branch-name

This keeps a local branch on your computer.

You can also checkout a temporary branch with:

$ git checkout [REFERENCE_NAME]/branch-name