Footprinting

In computers, footprinting is the process of accumulating data regarding a specific network environment, usually for the purpose of finding ways to intrude into the environment. Footprinting can reveal system vulnerabilities and improve the ease with which they can be exploited.Footprinting begins by determining the location and objective of an intrusion. Once this is known, specific information about the organization is gathered using non-intrusive methods. For example, the organization's own Web page may provide a personnel directory or employee bios, which may prove useful if the hacker needs to use social engineering to reach the objective. Conducting a whois query on the Web provides the domain names and associated networks related to a specific organization. Other information obtained may include learning the Internet technologies being used; the operating system and hardware being used; IP addresses; e-mail addresses and phone numbers; and policies and procedures.

http://en.wikipedia.org/wiki/Footprinting