There were 7.6 billion people in the world by the end of May 2018. Despite differences ranging from skin colour to religious belief, they were united by many things: the need to eat, breathe, sleep - and for billions of them, the desire to use social media.

At the end of last year, over a fifth of the Earth’s population (1.45 billion) was using Facebook each and every day. The social network was the first to surpass a billion registered accounts and currently has 2.2 billion monthly active users. That's more than a third of the world's population logging on each month.

Image: Statista/Facebook

But our desire to talk with, and in some cases rant and rave at, others is not solely confined to Mark Zuckerberg’s internet brainchild. It has been joined by a host of other platforms that are competing to attract us as users - and harvest our data so they can target us with lucrative marketing messages.

Video streaming service YouTube and encrypted messaging service WhatsApp (which is owned by Facebook) have 1.5 billion users each.

Image: Statista/We Are Social

Meanwhile, Facebook’s photo-sharing app Instagram has over 800 million monthly active accounts and blogging service Tumblr has an estimated 794 million monthly users on its site.

Making the numbers add up

Despite the huge number of us who already log on each day, social media use is still growing around the world.

But how precisely the numbers of users for individual platforms stack up compared with the world total seems confusing. For example, Facebook claims 2.2 billion registered uses while data compiled by We Are Social, which monitors platforms, shows there are likely to be 2.77 billion users across all social media platforms by 2019.

The answer to any apparent disparity will probably lie in how many registered accounts individuals and companies have between them. In the same way that many of us have more than one mobile phone number, so quite a few people who use social media are likely to be on more than one platform and may have more than one profile and log in for each site they subscribe to.

Image: Statista/e-Marketer

Who owns the data?

How we use platforms varies. For example, Facebook or Google+ are highly focused on exchanges between friends and family and are constantly pushing interaction through features such as photo or status sharing. Others like Tumblr or Twitter are all about rapid, often pithy "microblogs", while LinkedIn is aimed at professional and business users, and Pinterest aims to connect people with shared hobbies or interests.

But there are big questions that need to be asked as more of us sign up. How data is collected and used has come increasingly into focus in recent months, as have the profits social media companies make from us.

For example, Facebook reported profits had risen 63% to $5 billion in the first three months in a year-on-year basis, despite inquiries over the use of its users’ data in both Europe and the US.

The European Union’s General Data Protection Regulation comes into force on 25 May 2018 and will apply to every company handling EU citizens’ data, no matter where they are based. This law aims to give more power over data to consumers and has the potential to significantly change how companies relate to individuals and use their data in the future.