Google Inc. opened its Google+ social network to the world on Tuesday, removing the required invitation to join the search giant's rival to Facebook. Click google.com/+ to join in.

"For the past 12 weeks we've been in field trial, and during that time we've listened and learned a great deal," Google senior vice president of engineering Vic Gundotra said in a blog post.

"We're nowhere near done, but with the improvements we've made so far we're ready to move from field trial to beta... Anyone can visit google.com/+, join the project and connect with the people they care about."

Google said it made 100 improvements to the critically acclaimed Google+ since releasing the social network for field trial starting June 28.

Enhancements to Google+ included letting members take part in video-chat "Hangouts" using camera-enabled smartphones or tablet computers, or broadcast video presentations to groups of watchers using "Hangouts On Air." Hangouts now supports Android 2.3+ devices with front-facing cameras (and iOS support is coming soon). The new mobile app was rolled out to Android Market Tuesday.
Google also said it has woven its Internet search expertise into the social network by adding a query box. Typing keywords into the Google+ search box will return relevant people and posts, as well as popular content from around the web.

Facebook is the king of social networks with more than 750 million active users. But Google Plus is yet the most serious threat to Facebook's dominance. Google Plus's best feature is privacy -- the Circles feature lets you share and view content to and from explicitly identified groups of your contacts, and no one else. In addition, there's video chatting service Hangouts and other new features.

Google+ amassed 21 million users just three weeks after launching in invite-only mode. But there have been reports that activity in the new social network has subsided.

Since the unveiling of Google+, Facebook has added features to the site in order to further boost its huge user base. Facebook has teamed up with Twitter, now allowing 100 million Twitter users to update their accounts on their Facebook pages. Facebook earlier added a video and call service from Skype, has added a "subscribe" feature, and is reportedly putting a music service.

Is Google+ ruling the world? Or should it lower its forecast to something lower like... Maldives?

While Google is yet to settle on new land, Facebook has already built an empire.

Facebook (person to person), Twitter (person to public) and LinkedIn (workplace and career) have been able to coexist.

But Facebook and Google+ are redundant. So one of them will likely sink. Who will it be?