Google+ is a social networking site developed by Google in 2011 that has over 300 million monthly active users, making it the second largest social network globally. It includes basic social media features like profiles, status updates, and photo sharing, as well as video calls and a "+1" recommendation button. While marketing on Google+ provides advantages like influencing search rankings and reaching a wide audience, there are also risks like users ignoring advertisements, security issues, and competitors copying strategies. Overall, the document recommends that marketers utilize Google+ due to its large user base and potential advantages it provides.