Footprinting is the process in which an attacker gathers information about the target (a person or organization). It is the initial sub-phase of Reconnaissance phase of a Cyber Security attack.
Types of Footprinting
Passive Footprinting is process of gathering information about target without direct contact with the target from Internet, Open Source Intelligence (OSIN), Social Network etc.
Active Footprinting is process of gathering information about target with direct contact with the target using techniques like DNS integration, WHOIS, Social Engineering, Scanning (IP & Port Scans)