Scanning is typically an automated process that is used to discover devices such as PC, server and peripherals that exist on a network. Results can include details of the discovered devices, including IP addresses , device names, operating systems, running applications/services, open shares, usernames and groups. Scanning is often related to pre -attack or reconnaissance activities.
There are two types of scanning: Horizontal Scan in which the scanner scans for the same port on multiple IPs, and Vertical Scan in which the scanner scans multiple ports on one IP.