Yin Mei is an international consultant in Beijing at The Hoffman Agency , a multinational communications firm based in California. Follow her @meithoughts

Connections mean “power” in China. This is why social networks have become part of the relationship-building fabric of Chinese society. The numbers certainly bear this out. Roughly half of China’s 513 million netizens are using social networking sites, and all of these social networks are home grown.

While it’s true that the government makes it virtually impossible for foreign players to enter the social network market in China, some consumers use VPN services, which provide access to sites like Facebook. But even if China allowed outside players, Chinese companies have the natural advantage of understanding the nuance of the Chinese consumer. This is why the following five social media platforms are worth watching.

1. Sina Weibo

Simply describing Sina Weibo as the Twitter of China understates Weibo's unique capabilities and leadership role in the Chinese social media sphere. With more than twice as many users as Twitter, Sina Weibo is an essential platform to more than 22% of the Chinese Internet population. Part of its popularity can be attributed to the ability of users to include images and video, something Twitter is only now beginning to allow.

Today it’s the top platform for social discourse and a big driver for consumer activity. It's also a celebrity hub. Just as American celebrities communicate with their fans via Twitter, Chinese celebrities depend on Weibo as a way to connect with their fans and drive popularity. Interestingly enough, Bill Gates easily has twice as many followers as Tom Cruise on Twitter (Gates with 7,215,994 and Cruise with 3,077,444), but Cruise has 4,231,919 followers on Weibo, one million more than Gates.

2. Renren

Think of Renren as China's Facebook. After a fierce competition with Kaixin (www.kaixin001.com), Renren has come out on top. Originally, Renren lost a lawsuit about its domain name — www.kaixin.com — because it was so closer to Kaixin's. Still, Renren managed to retain ownership of that url, which now re-directs to its site. This move comes as Renren tries to expand beyond its predominantly student user base. With 147 million registered users and 31 million active users per month, Renren is poised to take over as the social networking platform for the college-educated population in China.

3. Tencent

Tencent is thought of as a platform for the masses and was essentially built on the QQ Instant Messaging service. With a QQ account, a user can get access to all of Tencent's different services. In other words, it's the equivalent of a social media hub. Yes, Tencent's social networking site Pengyou has lower numbers of active users than Weibo, and Renren. However, because of its multiple platforms, it maintains the biggest community in China in terms of sheer registered users.

4. Douban

Douban is the open forum popular among intellectuals for movie, music and book reviews, with around 60 million registered users and 80 million active users per month. These figures reflect that fact that Douban allows unregistered users to access about 80% of the site's content.

Two other platforms are in this same space and hoping to catch up. One is Diandian, which could easily become the next "Tumblr of China." The number of registered blog users on Diandian has hit five million since its founding in 2010. Another specialized social network making noise is P1.cn, an invite-only platform focused on the top 10% of Chinese earners. It has more than 2.7 million members.

5. Wechat

There’s no question that the mobile space will be the next battleground in China for social networks. That's because more than 69% of the Chinese population accesses the internet through mobile devices. Wechat — formerly known as Weixin — is a mobile voice and text app with social features like “friend discovery.” Although not initially a typical social network, Wechat has continually added more social networking features to its product, including a photo-sharing platform and an LBS component. Currently, it has more than 100 million users.

As social platforms adopt mobile apps to supplement their online platforms, some have decided to make mobile their focus. Several location-based services such as Jiepang (a FourSquare-like app) and Momo (a dating app) have gained popularity in the past year in their respective markets.