SMB / CIFS is a network protocol that allows sharing of files across a network of nodes. The protocol is based on a design where the customer requests it sends packets to the server, the server in turn sends response packets to the client.
The SMB / CIFS protocol is highly used by Microsoft Windows operating systems. Windows for Workgroups was the first Microsoft operating system using the SMB / CIFS and every Microsoft operating system since then have come to possess the ability to function as a server or client SMB / CIFS. The Microsoft operating systems use SMB / CIFS protocol for remote file operations (typically the mapping network drives), navigation (via the Network Neighborhood, authentication (Windows NT and 2000) and remote printing services. It is reasonable then to say that the core of Microsoft's native network-based services is the SMB / CIFS.