[Shimpy]

Originally Posted by bogie shooter

a backdoor in a computer system (or cryptosystem or algorithm) is a method of bypassing normal authentication, securing illegal remote access to a computer, obtaining access to plaintext, and so on, while attempting to remain undetected. The backdoor may take the form of an installed program (e.g., back orifice) or may subvert the system through a rootkit.

clear as mud