Facebook, the world's most popular social networking site, has introduced a Subscribe feature that allows users to subscribe to posts even from non-friends.

With the Subscribe feature, Facebook has become more like micro-blogging site Twitter and Microsoft's new social networking platform Google+.

The new Subscribe button can be used in three ways. It can be used to select what you see from others in News Feed, to hear from people who are not friends with you, or to allow others to hear from you, even in case you are not friends.

However, the Subscription button is not available on Facebook pages by default. Interested users need to opt in to enable the new button on their profiles.

Many believe that the introduction of the subscribe feature is a part of Facebook's efforts to fix complaints in response to escalating competition, especially after the emergence of Google+.

Principal analyst Greg Sterling, at Sterling Market Intelligence, said, "They're trying to address any and all reasons users might have for finding fault or deficiency with Facebook."

Competition in the social networking field is getting tougher day-by-day, but no rival platform is currently in a position to challenge Facebook, which boasts of its more than 750 million users.