A ticket to Super Bowl XXXV in Tampa Bay, Florida, didn't just get you a seat at the biggest professional football game of the year. Those who attended the January 2000 event were also part of the largest police lineup ever conducted, although they may not have been aware of it at the time. The Tampa Police Department was testing out a new technology, called FaceIt, that allows snapshots of faces from the crowd to be compared to a database of criminal mugshots.

Photo courtesy Visionics
Facial recognition software can be used to find criminals in a crowd, turning a mass of people into a big lineup.

The $30,000 system was loaned to the Tampa Police Department for one year. So far, no arrests have been made using the technology. However, the 36 cameras positioned in different areas of downtown Tampa have allowed police to keep a more watchful eye on general activities. This increased surveillance of city residents and tourists has riled privacy rights groups.

People have an amazing ability to recognize and remember thousands of faces. In this edition of HowStuffWorks, you'll learn how computers are turning your face into computer code so it can be compared to thousands, if not millions, of other faces. We'll also look at how facial recognition software is being used in elections, criminal investigations and to secure your personal computer.