"Social Plugins are one of the easiest ways to integrate Facebook with your website. The Like button is one of our most iconic products with over 10 billion views each day across millions of websites.
The Like and Share buttons both use the Facebook 'f' logo today. Our hypothesis was that more people would understand the thumbs up icon on the Like button, so we conducted qualitative and quantitative tests to measure them side-by-side. The results revealed an increase in engagement, so we are switching the Like button from the Facebook ‘f’ logo to the thumbs up icon."