Nielsen Entertainment released a study that found more than half of the nation's 117 million active gamers play online and 64 percent are women.

As in-game advertising develops, marketers may tap into the social aspect of online gaming with tactics such as word of mouth.

While gaming has conventionally been thought a solitary experience, the new study shows that gamers spend upwards of five hours a week playing games socially. The research also shows that although teenagers continue to comprise the largest percentage (40 percent) of Active Gamers, more than 15 million of these gamers (almost eight percent) are now 45 years or older.

Emily Della Maggiora, SVP of Nielsen Interactive Entertainment, says, "The expansion of next generation hardware and technology in the marketplace is simultaneously delivering new ecosystems of social exchange, interactive entertainment, media experiences and advertising models. We see everyday how important online gaming is in terms of connecting people and bringing communities of gamers together. From a simple battle in Halo to a more immersive communal experience, online gaming has the power to unite gamers across the street and/or around the world."