Can you explain what git reset does in plain English?

In general, git reset function is to take the current branch and reset it to point somewhere else, and possibly bring the index and work tree along.

- A - B - C (HEAD, master)
# after git reset B (--mixed by default)
- A - B (HEAD, master)      # - C is still here (working tree didn't change state), but there's no branch pointing to it anymore

Remeber that in git you have:

• the HEAD pointer, which tells you what commit you’re working on
• the working tree, which represents the state of the files on your system
• the staging area (also called the index), which “stages” changes so that they can later be committed together

So consider:

• git reset --soft moves HEAD but doesn’t touch the staging area or the working tree.
• git reset --mixed moves HEAD and updates the staging area, but not the working tree.
• git reset --merge moves HEAD, resets the staging area, and tries to move all the changes in your working tree into the new working tree.
• git reset --hard moves HEAD and adjusts your staging area and working tree to the new HEAD, throwing away everything.

Use cases:

• Use --soft when you want to move to another commit and patch things up without “losing your place”. It’s pretty rare that you need this.
• Use --mixed (which is the default) when you want to see what things look like at another commit, but you don’t want to lose any changes you already have.
• Use --merge when you want to move to a new spot but incorporate the changes you already have into that the working tree.
• Use --hard to wipe everything out and start a fresh slate at the new commit.