Many of us use the app as a convenient way to organise group plans - others are glued to it constantly - but who do you spend the most time talking to?
What did we do before WhatsApp ? Remember the days when sending a picture over SMS cost you an arm and a leg, group plans were made by three-way phone calls and you didn't have those glorious blue ticks to let you know if someone had received your letter in the post.
Earlier this month it was revealed that the social networking app now has over 1 billion users - that's one seventh of the entire planet's population.
Of course, there are certain people who are always there for you on WhatsApp. If you see a funny meme on Instagram, who do you immediately send the screenshot to?
When you turn up to a date early and message someone so you don't look like a loser who has nobody to talk to, who do you turn to first?
There's an easy way to find out who your WhatsApp bestie is - and it's hidden within the app itself.
All you have to do is go to the settings tab, then 'Account' and 'Storage Usage'.
Storage usage is a handy little section that gives you an exact breakdown of how many messages you've shared in each of your current chats.
One thing to note is if you've cleared any conversations (for example, when trying to erase an ex from your life) then the total will revert back to zero.
What's the point? Well, there's no real merit to finding this out. But it might be nice to tell your WhatsApp bestie that they're your number one.