Video and computer games are an almost inescapable element of life for any modern child. Even parents who don’t have game machines and carefully control their children’s media exposure will, at some point, have to make some choices about games.

Do you let your children play them? What kind? How much? How can you know what’s good and bad?

First, we’ll explore the information available to parents, and then we’ll look at how to use it to make the right decisions for your family. Games are, in fact, one of the most transparent media. Between the self-imposed rating system, game “descriptors” and various parent- and values-oriented media sites, there is certainly no shortage of information.

The Entertainment Software Rating Board (ESRB) was created in 1994 in response to concerns and criticisms about violent game content. As with the motion picture ratings system, it is a completely voluntary system in which publishers pay to submit their games for a rating.

The rating board does not usually play the games, relying instead upon responses to a detailed questionnaire and video of all possible areas of concern.

This process works most of the time, and major publishers do not attempt to deceive the rating board by hiding content. It’s a flawed system, but it usually works.

There are six ratings:

• EC (Early Childhood, age 3 and up)

• E (Everyone; no content worries)

• E10 (Age 10 and up; may contain cartoon or fantasy violence and some crude humor)

• T (Teen, age 13 and up; may contain violence, crude language, minimal blood, some sexual themes)

• M (Mature, 17 and up; intense violence, strong language, sexual content)

• AO (Adults Only, 18 and up; prolonged violence, strong sexual content)

Basically, E is rated “G,” E10 is “PG,” T is “PG-13” and sometimes “R,” M is always “R” and sometimes worse, and AO is “NC-17/X.”

Retailers will not carry unrated games, and most will not carry games with the AO rating. Sony, Microsoft and Nintendo have all barred AO games from appearing on their systems.

The ratings themselves are helpful at a glance, but the 30 descriptors are what make the ESRB system truly useful. Some may find them confusing at first, but a quick trip to ESRB.org will clarify the nuances and meanings among the various categories.

Every element that might be of concern is addressed: humor, lyrics, language, controlled substances (alcohol, tobacco and drugs), gambling, sex, nudity and violence.

Each element has various degrees of severity. Sexuality, for example, ranges from “suggestive themes” (innuendo and hints of sexuality) to “strong sexual content” (explicit and frequent sexual behavior).

For instance, ERSB descriptors rate three kinds of blood: “animated blood” describes “discolored and/or unrealistic depictions,” “blood” is a realistic depiction, and “blood and gore” is realistic blood with “mutilation of body parts.”

The only place where the ESRB ratings have failed is in the distinction between M and AO-rated games. The AO rating is rarely imposed, and almost always reserved for titles that want the rating in order to appeal to an adult audience. Only 23 AO ratings have been issued to date, almost all of them for pornographic games where the game makers wear the AO rating as a badge of honor.

That “Grand Theft Auto IV” escaped an AO rating despite its extreme depiction of sex (including lap dances and prostitution) is one of the great failures of the ESRB, and it means that parents can no longer trust the distinction between M and AO ratings without further research.

If a game is rated M, particularly for “strong sexual content” and/or “intense violence,” you must assume it is out of bounds for anyone under the age of 18.

The AO rating is almost always reserved for sexual content. It has only been given twice for “wanton and gratuitous violence.”

Banning AO-rated games from the Xbox and PlayStation may seem like good corporate citizenship, but it’s a mistake. Although it sounds counter-intuitive, parents would actually be better served if the major console makers allowed AO-rated games on their systems.

Since parents can block such games from being played on their machines, it wouldn’t effect what comes into the home. It would, however, make the AO rating into a valid category and allow less extreme content to slip into M-rated games.

Meanwhile, the retailer ban on AO games would force larger companies to moderate their content for big-budget releases. If the AO rating was viable and actually allowed on game systems, publishers would be forced to tone down their games to earn an M in order to get into as many stores as possible.

Thus, the most dangerous aspects of “Grand Theft Auto IV” or “Manhunt II” would be available to a hard-core adult audience — but kept out of most American homes. I know 10-year-olds who are playing this game because parents aren’t taking the M rating seriously enough. A valid AO rating might change what these children actually see.

Thomas L. McDonald is

editor-at-large of Games magazine and a catechist in the Diocese of Trenton, New Jersey.