On Wednesday, Facebook announced it will acquire the messaging app WhatsApp for $19 billion as part of Mark Zuckerberg's strategy to remake the social network into a mobile company. (The deal involves $16 billion in cash and stock and an additional $3 billion in restricted stock for employees that will vest over four years.) It was an expected move, as the social network has seen its own messaging capacities diminished by the popular app and others like it. But the acquisition also marks Facebook's priciest purchase to date. 

Below is a timeline tracking Facebook's most notable acquisitions by the numbers. You'll notice a few startups were left off this graphic, as their acquisition prices were undisclosed. However, it's important to note how each company has shaped Facebook's agenda as it becomes the most visible online platform in the world. Among them are SportStream, which vied to compete with Twitter as a source of real-time sport stats and conversation; Glancee, a social discovery app that helped users meet others with similar interest; and Lightbox, the Android photo-sharing app that generates blogs with users' own content. 

Below is a timeline of the big buys with their estimated deal values (not scaled to proportion): photo app Instagram; mobile-development tool maker Parse; mobile-app analytics company Onavo; link-sharing service Branch; and WhatsApp.