Social networks have transformed the way we interact and communicate. We use them more than ever, moving from channels in which we talk with friends to true revolutionary means - see the example of the role of social networks in movements such as the Arab Spring.

To celebrate Social Media Day, here are the most popular social networks by number of users.

Facebook- 2, 23 billion users.

Facebook is an American social network launched on February 4, 2004 by Mark Zuckerberg and his college colleagues at Harvard. It is the most used social network in the world.

Youtube - 1.5 billion users.

YouTube is an American video-sharing site created in 2005 by three former PayPal employees. Google bought the site in November 2006. Although many people do not consider Youtube a social network, the site defines itself as so, allowing users to upload, view, sort, share, and comment on videos. Over the years, Youtube has turned out to be a community where people interact based on their interests.

Whatsapp - 1.5 billion users.

WhatsApp Messenger is a free messaging service. The app can be used on mobile devices or in PCs (whatsapp web) and allows sending text messages, audios, documents, images, etc. Whatsapp is very popular due to its messaging encryption system, which is based on the generation of unique security keys through the Signal protocol developed by Open Whisper Systems.

Facebook Messenger - 1.3 billion users.

Facebook Messenger is an application and messaging platform, originally the Facebook chat. Users can send messages and exchange photos, videos, stickers, audio and files, and react to other users' messages and interact with bots. The service also supports voice and video calls.

Instagram - 1 bilion users

Instagram is a social network originally created to share images in a ratio of 1: 1. Size and proportion restrictions were mitigated in 2015. Instagram also added messages, the ability to include multiple images or videos in a single post, as well as "Stories" - similar to its main competitor Snapchat.

WeChat - 980 million users.

If you've never heard of WeChat, do not worry, it's normal. WeChat is a Chinese messaging, social networking and mobile payment application launched in 2011. Nowadays it is one of the most used apps in the world, mainly because it is used in the most populous country in the world. Apart from China, it is also Bhutan's most popular messaging application.