Penetration Testing, also called pentest, is a methodology of testing the vulnerability of a network or system infrastructure by simulating real time outside attacks.  These attacks are performed as thoroughly as possible to try to create a true sense of the security, or lack of, surrounding a system.  There are a variety of testing software, hardware, and mediums to which penetration testing can be performed.   Pen Testing should be routinely performed on all system regards of perceived security risks.  Obviously the financial, medical, and governmental agencies and corporations lay out the most intrusive penetration testing requirements as their data tends to be much more sensitive than most.  However in recent memory both e-commerce and educational sectors have done a great deal of catching up in terms of placing self-standards in the area of penetration testing and network security.

Backtrack Linux itself is a self-contained penetration testing tool encompassing tools for brute forcing, wifi cracking and much, much more.