See the meta FAQ introduction if you don't have any idea what Samba does.
Samba has many features that are not supported in other CIFS and SMB implementations, all of which are commercial. It approaches some problems from a different angle.
Some of its features include:
Look at the manual pages included with the package for a full list of features. The components of the suite are (in summary):
the SMB server. This handles actual connections from clients, doing all the interfacing with the authentication database for file, permission and username work.
the NetBIOS name server, which helps clients locate servers, maintaining the authentication database doing the browsing work and managing domains as this capability is being built into Samba.
the scriptable commandline SMB client program. Useful for automated work, printer filters and testing purposes. It is more CIFS-compliant than most commercial implementations. Note that this is not a filesystem. The Samba team does not supply a network filesystem driver, although the smbfs filesystem for Linux is derived from smbclient code.
a little 'glue' program to help the server run external programs.
a program to test server access to printers
a program to test the Samba configuration file for correctness
the Samba configuration file
many examples have been put together for the different operating systems that Samba supports.
DON'T neglect to read it - you will save a great deal of time!