Samba is a set of tools to share files and printers with computers running Windows. It implements the SMB network protocol, which is the heart of Windows networking.
Samba can act as a server for Windows (or Samba) clients: share folders and printers, including PDF pseudo-printers so all the computers in your network may write PDF files, Samba can act as a domain controller in a Windows network (authenticating users, etc.) As well as, do some more complex stuff, such as using a Windows domain controller to authenticate the users of a Linux/UN*X machine.
Link: Community Ubuntu Documentation
Tags: Linux, Networking, Tools, Windows