Footprinting (also known as reconnaissance) is the technique used for gathering information about computer systems and the entities they belong to. To get this information, a hacker might use various tools and technologies. This information is very useful to a hacker who is trying to crack a whole system. Footprinting (also known as reconnaissance) is the technique used for gathering information about computer systems and the entities they belong to. To get this information, a hacker might use various tools and technologies. This information is very useful to a hacker who is trying to crack a whole system. When used in the computer security lexicon, 'Footprinting' generally refers to one of the pre-attack phases; tasks performed before doing the actual attack. Some of the tools used for Footprinting are Sam Spade, nslookup, traceroute, Nmap and neotrace.