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In 2002, more than 221 million computer and video games were sold in the United States, and this holiday season parents are expected to flock to stores to grab up these interactive stocking stuffers.

But do mom and dad really know what they're wrapping in shiny bows and festive paper?

The National Institute on Media and the Family recently released a study showing that 87 percent of youths in grades 4 through 12 play video games, and only about 50 percent of parents understand the rating system that reflects the content of the games.

Experts who monitor the industry say that before parents rush to the mall to pick up that hot new video game for Junior, they should be aware of how much sex and violence the games contain.

"Check the ratings — they're fairly self explanatory," said Patricia Vance, president of the Entertainment Software Rating Board (search), which has created a rating system for video games akin to movie ratings.

Through the lettered system, which ranges from "EC" for early childhood games aimed at young kids to "M" for mature audiences only, the ESRB gives parents tools for gauging the amount of sex and violence in video games. And while parental awareness is on the rise, Vance said, many moms and dads don't look at the ratings as hard as they should.

Parents may not use the ratings every time, "but they're aware of them," said Vance. "We need to work harder to get them to really understand it every time."

At the tamest end of the spectrum are the "EC" ratings for kids age 3 and older; "T"-rated games may contain violent content, mild or strong language, and/or suggestive themes and are meant for teens age 13 and over; "AO" is for adults only and may include graphic depictions of sex and/or violence. "E" is for everyone age 6 and up; and "M" means games contain mature content suitable for those 17 and older.

Most video games also provide content descriptors on the back of their packaging, such as "alcohol reference," "blood and gore," "drug reference," "gambling," "intense violence," "mature sexual themes," "nudity" and "tobacco reference." Check the ESRB's Web site for in-depth descriptions of what these descriptors mean.

"Those are great guidelines and certainly with the content descriptors, parents can make an informed decision about what's best for them and their kids," Vance said.

Some parents, like M.C. Keegan-Ayer of Frederick, Md., have worked to educate themselves on what their kids are playing.

"When my oldest child, who's now 14, started buying them, I really wasn't aware of it, but as he's gotten older and wanted older games, I have become much more cognizant of the ratings and what they mean," Keegan-Ayer said. "Even though a game may have a 'T' rating, which technically could be acceptable for him, there may be things in the game I just don't want him to be exposed to."

Although the ESRB rating system isn't perfect, Warren Buckleitner, editor of the Children's Software Revue (search), said it's the best system in place now.

"I think the ESRB is pretty good," he said. "But I think the categories are too general and the real value of the ESRB system are the descriptors, which are on the back of the box and parents need to read that carefully."

The National Institute on Media and the Family (search) says not enough parents pay attention to what games their kids are playing. But the Entertainment Software Association reports 96 percent of parents surveyed who have kids under 18 say they are paying attention, and 60 percent say they actually play the games with their kids at least once a month.

In terms of kid-friendly fare, the media institute recommends these games: SimCity 4, The Legend of Zelda: The Wind Waker, NBA Street Vol. 2, Top Spin, Rise of Nations, Madden 2004 and Mario & Luigi: Superstar Saga.

The Legend of Zelda: The Wind Waker, for example, is an adventure game starring a cartoon boy who must save the world from the forces of evil. At his disposal is an arsenal of innovative tools such as a telescope, a boomerang and a magic wand. Link, the main character, travels to different lands where he gets to know merchants, finds treasures and gets more information for his quest.

Games to steer clear of, according to the institute, include: Manhunt, Road Kill, Outlaw Volleyball, Dead or Alive Xtreme Beach Volleyball, Def Jam Vendetta, True Crime: Streets of L.A., Max Payne 2 and Postal 2.

On cd-wow.com, for example, the description of Manhunt says: "The ultimate rush is the power to grant life and take it away, for sport … this is a brutal blood sport."

While there are no laws compelling retailers to enforce the rating system, some companies such as Best Buy, EBGames and CompUSA have rating system signs in place for the shopping season.

"We're focusing very much on making sure retailers have reminder messages and descriptive graphics where the product is displayed," Vance said.

But all experts say the best defense against exposing kids to inappropriate games is knowledge. Parents should familiarize themselves with the ratings system and study the games. Talking to kids about why they want to play particular game can also help.

"We always recommend that parents play games with their kids," Vance said. "It's very informative, it keeps them up-to-date and it's fun."