In addition to David's response, there are also differential backups,
which can reduce the number of restores needed to get back to a certain
point. For example, you can do a full backup once a week (eg. Sunday),
a differential once a day, and log backups every hour. Then to get back
to Tuesday, you would restore only Sunday's full backup and Tuesday's
differential, rather than Sunday's full backup and all the log backups
from Monday and Tuesday. See "Reducing Recovery Time" in Books Online
for more details.
Check out the "Backing Up and Restoring Databases" section in Books
Online - there's lots of good information there.
Simon