git for versioning

[Manish]

  2008/7/30 martin f krafft :
  > also sprach Rustom Mody [2008.07.30.1322 +0200]:
  >> If I want to work on changes in the common part, I check out (a tag
  >> for) the point before the branch (as a detached head??)
  >> Work on that and then what?? Thats my question.
  >
  > Don't you have a common branch, like master? You can't work with
  > detached heads, so you'd need to make a new branch there.
  >
  > Once you made changes to such a branch, then you either merge this
  > branch into the branches for Beth and Albert and so on, in turn, or
  > you rebase each of these branches onto the tip of the branch you
  > worked on.

I am also new to git so just to confirm.  Merge will leave us with one
less branch whereas a rebase will move our changes on top of the
changes of other branch.  Right?

Also if a document is modified in master and also modified in branch
A, then when we rebase A on top of master what will be the state of
contents of A?  Same as master or same as A or will a merge be
performed?

-- Manish