What is fbclid? the new facebook parameter

For two days, I have noticed that the URL that I publish on Facebook, there is a parameter is added:?fbclid=uFCrBkUgEvKg…To be more precise something like: http://example.com?fbclid=uFCrBkUgEvKg… Does anyone know what this parameter does?What is it for and what is the use of the developers? Thanks for your comments.