According to the book of Revelations, the Beast causes the whole world to worship the Anti-Christ (or at least his image) and restores him to health after he receives a wound in the head.
The population of the world cannot buy or sell anything without having the mark of the Beast in their foreheads.
I have often thought that the appellation "Beast" may be a metaphor for something that is not human.
Try this on for size: Take the letters of the English alphabet and assign to each a value based on the number six: A is 6, B is 12, C is 18, and so forth.
Now, take the values of the letters to the word "computer" and total them up.
The sum is 666.