Since Google Plus (Google+) publicly debuted on Sept. 20, 2011, Google’s fledgling social network has experienced some major ups and downs, but less than a year and a half later, the network has flourished to become the No. 2 social network in the world.

According to a new report from Global Web Index, Google Plus boasted 343 million active users in Q4 2012, a 27 percent jump from the year prior to make it second among all social platforms in terms of active usage. Even better for Google, YouTube, which had not previously been tracked as a social network, was the world’s No. 3 social network with about 300 million active users.

Facebook is still far and away the benemoth of all social networks, with almost 693 million active users (from its 903 million accounts) -- 51 percent of the global Internet population -- but Google and its services are catching up: Google Plus and YouTube are being used by 25 percent and 21 percent of the global Internet populace, respectively; Twitter is also used by 21 percent of the total, global Internet.

Google Plus and YouTube benefit each other’s active user base since both are deeply integrated into one another -- a prime example of Google’s intelligent linking of its services -- but neither platform can say it is the fastest growing social network. That honor would go to Twitter, which grew roughly 40 percent to 288 million users across 31 different markets, which comprises roughly 90 percent of the global Internet population.

What This Growth Means For Google

Not too long ago, Google Plus was against the ropes, struggling to maintain traffic and momentum after its public debut. The site, at the time, looked very plain and lacked any real key differentiator from Facebook, besides its video chat offering, Hangouts.

In about a year and a half, Google has done many things to beef up its social offering, giving it a new design, new technology and a really sleek mobile application. But the best thing Google did in the last 16 months -- something its competitors should learn from -- is learning how to seamlessly integrate its services.

Google Plus surpassing Twitter to become the No. 2 social network speaks less to Google Plus, the project, and more to Google, the company.

Being the No. 2 social network is a testament to Google’s presence on the Internet; even if people don’t care about maintaining their Circles or fleshing out their profiles, users still need their Gmail, Google Docs and Google Maps. Google finally realized that Google Plus shouldn’t be another branch on the tree, but rather a way to give its trunk (search) some personalization and personality.

People are clearly learning to trust Google, but the rise of Google Plus also has a great deal to do with the rise of phones and tablets. Google Plus may be the best mobile app Google has ever made: It’s colorful, easy to navigate and enjoyable to use. Considering how people love to share content via mobile, Google Plus is an excellent place to do it. Global Web Index said it will follow up its report with a separate one about Google Plus, which is likely to detail some of its desktop versus mobile traffic.

As it stands now, Facebook keeps proving resistant to fatigue, while Twitter is only growing stronger as more people depend on it to break and disseminate newsworthy information. Those two networks are the largest and fastest growing, respectively, but having been in the social business for less than two years, Google’s not doing so bad itself.