US-based firm had originally started the messenger service as a chat feature on the website but later rolled it out as a standalone mobile app.

"Messaging is an important part of how people stay connected and since Messenger launch in 2011, we've been passionate about giving people a faster and more expressive way to communicate," Facebook Director of Product Management Peter Martinazzi said in a blog post.

Today, more than 500 million people are using Messenger each month, he added.

"Messenger was the first of our standalone apps, and unlike our core Facebook apps, it focused on one use case – messaging. It is just as fast as SMS but gives you the ability to express yourself in ways that SMS can't," he said.

Using Facebook Messenger, users can send stickers or videos, take selfies and chat with groups.

"We've also continued to improve speed and reliability. Updates to Messenger ship every two weeks so it continues to evolve and improve," he added.