Reconnaissance is the phase in which an attacker gathers information about the target (a person or organisation).
Types of Reconnaissance
Passive Reconnaissance is process of gathering information about target without direct contact with the target from Internet, Open Source Intelligence (OSIN), Social Network etc.
Active Reconnaissance 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)