A git rebase is like a git merge done through rose-coloured glasses.

You can see it for yourself by doing this little experiment. Assuming the alice directory is a valid git repository:

$ cd alice

$ echo "foo" >> rebase.episode

$ git add rebase.episode ; git commit -m 'begin rebase episode'

$ git checkout -b monsters

$ git branch

* monsters

master

$ echo "ghoul" >> ghoul.txt

$ git add ghoul.txt ; git commit -m 'ghoul'

$ git checkout master

$ echo "rogue" >> rogue.txt

$ git add rogue.txt ; git commit -m 'rogue'

$ git checkout monsters

$ echo "dragon" >> dragon.txt

$ git add dragon.txt ; git commit -m 'dragon'

$ git checkout master

$ echo "paladin" >> paladin.txt

$ git add paladin.txt ; git commit -m 'paladin'

You have now emulated a bunch of activity on two separate branches of a git repository.

Create a copy of the repo so that you can perform two separate git actions.

$ cd ..

$ cp -r alice alice-merge

$ cp -r alice alice-base

Do an honest merge:

$ cd alice-merge

$ git checkout master

$ git merge monsters

The log shows you an accurate representation what got merged, and how all those changes came to be:

$ git log --oneline

123456 Merged monsters into master

789101 paladin

112131 dragon

415161 rogue

718191 ghoul

7ef217 begin rebase episode

Now perform a rebase.

$ cd ../alice-base

$ git checkout master

$ git rebase monsters

The log displays a different story than what really happened.

123456 Merged monsters into master

8e9122 paladin

21d163 rogue

912a3f dragon

51c098 ghoul

7ef217 begin rebase episode

Better? Worse? YOU DECIDE!