Office pools have become popular across the country since the NCAA tournament field was announced on Sunday. They may appear harmless, but office pools are considered illegal and distract employees from doing their jobs.

In office pools, people generally pay for a bracket sheet, and then pick the teams they expect to win, down to one team. In the end, the person who picks the most teams who get into the Final Four and picks the overall winner goes home with the pool of cash.

While the amount of money that is payed to fill out a bracket ranges from a $1 to $10, it quickly adds up when one out of every 10 Americans fills out a bracket to win money on the tournament that wraps up April 6 in Lucas Oil Stadium in Indianapolis.

Most people participate in office pools for the money or for bragging rights, but others say it makes the games more interesting. Even though most of the pools are small, attention given to the tournament over the next three weeks will cause billions in lost productivity at U.S. companies as employees watch the games rather than do their jobs.

Nearly half of all U.S. workers have participated in an office pool at some point, according to a recent survey by Spherion Corp., a recruiting and staffing company based in Fort Lauderdale, Fla. The survey found that 75 percent of those who participate in office pools spend less than $20 – while 8 percent said they spent $50 or more.

Any type of sports betting is illegal and law enforcement officials acknowledge that office pools are hard to monitor and it isn't something that is given top priority. If a person is caught, which is very rare, they are usually issued a warning.

The NCAA is strongly opposed to office pools because it gives athletes mixed messages and it has an impact on the integrity of the game. NCAA rules prohibit college athletes, coaches and administrators from participating in any kind of sports betting – no matter how innocent.