Why does rebase have a link to original branch?

[andrewducker]

If I have a branch, and rebase that branch on master, then it correctly produces a new set of commits following on from the tip of master.  But it also has a "merge commit" which links back to the original branch.

Why is that merge commit necessary?  Why not just have the new set of commits, rather than keeping the old ones around?

[Manju]

Here is some info on merge vs rebase which might be of help - https://www.atlassian.com/git/tutorials/merging-vs-rebasing

And the official rebase documentation of git - https://git-scm.com/book/en/v2/Git-Branching-Rebasing