The Facebook "like button" is so popular - viewed 22 billion times per day according to The Verge- it took six months for product manager Ling Bao to redesign it from this:

To this (or see our own site's link directly below):

The new button, essentially a darker shade of blue with the Facebook "f" replacing the thumbs up sign, debuts today though it will update across all platforms over a period of several weeks, according to The Verge.

Why Facebook chose to undertake such a tedious project, which debut Thursday, remains somewhat unclear. Few articles on the subject have even asked the question. A new hybrid feature allowing users to like and share, or simply "like-share" may explain why the social media company altered a button it hasn't touched since its debut in 2010 and fantastic success since. See below for the new button, which Facebook's promotional page claims will "help people share more great content across the web." 

How the project took so long? Bao can explain that.

"'They're just buttons, why did it take so long?' you ask, but getting a design that works across all these websites at different scales and in different browsers is quite a herculean task," said Bao, who calls the like feature "one of Facebook's most valuable brand assets."

A single alteration or changed pixel has the potential to disrupt one or more of the many browsers (both new and old) or hundreds of different languages supporting Facebook and the like button, according to The Verge.

"It's not easy designing a button used by the whole internet," Bao said. "This product has a lot of unique constraints, and is used by so many sites in different contexts."

There's also the process of getting the new designed approved by every member of the Facebook hierarchy, from designers, vice presidents, lawyers, all the way to Mark Zuckerberg, The Verge reported.