Google+ is also known as Google Plus or G+.
Google+ has been described as Google's attempt to take on Facebook. Just as you can "like" a site and the site you like then appears on your Facebook page, so too can you "+1" a page which then appears on your Google+ account.
Google integrates many of its other products into Google+ as well. As with other social media sites you can post updates, include biographical information, upload photos and follow other people's updates, and you can also create circles of friends.
Google launched Google+ Pages so that businesses can have a page on Google+ in the same way they have pages on Facebook.
Google+ is growing fast and Google are incorporating many of their other products into it. It therefore has the potential to become a big player in both social media and in online searching as a whole.