As used on the Internet:
1) As a verb, the practice of trying to lure other Internet users into sending responses to carefully-designed incorrect statements or similar "bait." In a real example, a Usenet newsgroup contributor mentioned the discovery of an ancient African carving containing a list of prime numbers. The contributor further listed some of the prime numbers found and included some numbers that, in fact, are not prime numbers. Other contributors then sent serious replies, correcting the list of prime numbers cited.
2) Also as a verb, as a synonym for "surf."
3) As a noun, in emulation of the small mischievous figures of Scandinavian legend, a figure (or one of a group of figures) that you can pretend to be in the chat groups and games called MUD and MOO and their variations.