Footprinting is the technique of gathering information about computer systems and the entities they belong to. This is done by employing various computer security techniques, as:
When used in the computer security lexicon, "footprinting" generally refers to one of the pre-attack phases; tasks performed prior to doing the actual attack. Some of the tools used for footprinting are Sam Spade, nslookup, traceroute, Nmap and neotrace.