Gradually but inexorably, Facebook has been changing the algorithm that determines which posts its users see and in what order.
The company says it is doing this to improve the quality of the main news feed that each of its billion users sees. Brands that rely on Facebook to boost clicks to their sites claim the changes were made to force them to pay for better visibility and boost Facebook's revenues.
Almost certainly, both are right.
The issue has been boiling below the surface for a while now, but it has suddenly made the news via -- what else -- a viral post.