Pull
hg pull [-u] [-f] [-r REV]... [-e CMD] [--remotecmd CMD] [SOURCE]
A pull propagates changesets from a "remote" repository (the source) into a local repository (the destination). It can optionally update the working directory (specify option -u or --update).
The source (or "remote") repository may be located on the same or on a different computer. In the latter case, the changes are pulled over the network using the protocol specified by the provided URL of the remote repository.
The source may also be a bundle file.
Pull transfers only changesets which are missing in the destination repository.
General rule of thumb: Finish your work and commit it before you start pulling in stuff from the outside world.1
Help text: http://www.selenic.com/mercurial/hg.1.html#pull
See also: Push, CommunicatingChanges, TutorialShareChange
1 from the posting "abort: push creates new remote heads!" by Martin Geisler (2008-04-17, Mercurial mailing list)
