Google+ has overtaken Twitter as the world's number two social network, according to British research firm Trendstream's Global Web Index. Google's social network attracted more than 343 million active monthly users in December, as much as 25 per cent of all internet users globally.

  1. Facebook: 693 million monthly users, 51 percent
  2. Google+: 343 million monthly users, 25 percent
  3. Twitter: 288 million monthly users, 21 percent
  4. YouTube: 280 million monthly users, 21 percent

By way of comparison, Twitter was used by 288 million people in December, or 21 per cent of all internet users. The micro-blogging service's reach grew by 40 per cent from June 2012, according to the index.

YouTube also saw big growth, virtually tied with Twitter at 280 million monthly users. Google's integrated platform likely helped drive users to both of the company's social networks, letting users access both sites with a single sign-on.

Facebook remained at the top of the internet heap, with 693 million active monthly users, or 51 per cent of the world's total internet users. The social network says it has approximately 1 billion total users.

Not every social network grew, however. Regional networks like China's Weibo, RenRen and Qzone saw their monthly user bases shrink as much as 50 per cent. Trendstream tracks 8 different social networks that operate only in China, each capturing over 5 per cent of global online users.