Head
hg heads
A head is a [:ChangeSet:changeset] with no children. The [:Tip:tip] is the most recently changed head. Other heads are recent [:Pull:pulls] into a [:Repository:repository] that have not yet been [:Merge:merged].
If you have just made a [:Commit:commit], that commit will be the tip. Alternately, if you have just pulled from another repository, the tip of that repository becomes the current tip.
Mercurial supports [:MultipleHeads:multiple heads] concurrently within a single repository.