What is the difference between a merge and a rebase?

About

merge and rebase are two commands that are designed to integrate changes between two branches (remote or local)

They have one difference:

• Rebase will rewrite the commit history (log) to make it linear
• while merge will not.

Example

Imagine this commit history (log) ¹⁾ with a remote and a local branch where the commit in the remote branch will be integrated into the local branch.

- A - B - C - D - remote HEAD
    \
      E - F - G - local HEAD

After a merge, the commit history (log) will look like:

- A - B - C - D - remote HEAD
    \                         \
      E - F - G - local HEAD - new local HEAD

After a rebase, the commit history (log) will look like:

- A - B - C - D - remote HEAD - E' - F' - G' - local HEAD'

Advantage / Disadvantage

There is a trade-off:

• The advantage of a rebase is that the history is easier to follow.
• The disadvantage is that the code in commit G may not work nicely with the code in commit B.