If you're a regular WhatsApp user you might have noticed this weekend that the service was down for long periods - not great timing, given it just announced a $19 billion deal to be acquired by Facebook.
So what happened?
WhatsApp founder Jan Koum on Sunday issued an apology and blamed a network router for Saturday's outage of the mobile messaging app. Koum wrote
"We are sorry about the downtime. It has been our longest and biggest outage in years. It was caused by a network router fault which cascaded into our servers. We worked with our service provider on resolving the issue and making sure it will not happen again".
But is that the whole story? Check out the video above for a deeper look at how avoiding downtime is crucial for WhatsApp - and now Facebook - to make sure its value remains high for years to come.