Capture the Flag

More than 6,000 hackers and other attendees gathered in Las Vegas this weekend to party and compete at Defcon, the world's largest hacker convention.

Here, teams battle it out in the confab's Capture the Flag game, organized by a group called Kenshoto. In this computer security war game, the goal is to attack rivals' networks while simultaneously defending one's own.

To participate, would-be entrants must score well in a prequalifying round by answering questions ranging from hacker trivia to computer forensics to Web server administration.