MD5 Collisions, visualized

"In computer science, a hash collision or hash clash is a situation that occurs when two distinct inputs into a hash function produce identical outputs."

Why you shouldn't be hashing with MD5 anymore if you have access to the SHA-1 algorithm. MD5 collisions can be made in hours or minutes on a standard notebook computer. This basically renders the hash useless for highly sensitive information.

Link:
http://www.links.org/?p=6