If at least once you dreamed of making a hit app that explodes in popularity, gets 1 million downloads in one week and gives you instant fame and fortune, you are not the only one. However, making a successful app takes a lot more than that and, more important, keeping the millions of users you acquired active is a really difficult task. On a distant position that goes beyond the horizon there's a "club" made of apps and services that have more than a billion monthly active users.
Facebook surprises us every day and almost every number associated with it is huge, including its revenue and profit growth, and CEO Mark Zuckerberg's net worth. The social network has 1.6 billion monthly active users, but the most impressive stat is that more than a billion users log in to Facebook every day. However, the social network is not done yet with the billions: Facebook Groups just joined the club at the end of January, and WhatsApp reached the 1 billion mark on Monday. If you add Instagram, with around 400 million monthly active users, and Facebook Messenger with 800 million, Facebook has a huge reach.
Google is another company that amasses billions and billions of users, although, just like Facebook, the numbers overlap because most users are active in more than one service or app. The most iconic Google product is search, which is an intrinsic part of the internet for a lot of people around the world (you don't say "Bing it", do you?). Google Search has more than 3 billion searches per day, which can give you an idea of how big it is. Then you have Android, with 1.4 billion users, and the Play Store coming in close, which makes a lot of sense since people install apps from there. YouTube also has more than a billion users each month and around 1/3 of all internet users go to the website to watch videos. Chrome and Gmail recently joined the club and each has more than a billion users now. Microsoft is also in the game and Windows, across several versions, gets 1.5 billion users, while Office tools have 1.2 billion users combined.
Other services still don't have at least one billion users, but they should get there soon. Aforementioned Facebook Messenger is almost there and with 800 million users and growing fast, it shouldn't take long. Chinese QQ is in the same situation as Messenger, with more than 800 million users and growing, while WeChat, also from China, comes next with 650 million users and getting there quickly.