Millions of users were unable to access their accounts.
Users in some countries also had difficulties accessing photo-sharing app Instagram.
Facebook said it believed its own engineers had caused the problem, downplaying claims that a hacking group had been responsible.
The sites appeared to have been unavailable for about 40 minutes before coming back online.
Dating app Tinder, which relies on Facebook to provide its service, was also affected by the problem.
A hacker group called Lizard Squad had tweeted about the services going offline, leading to reports that it might have been responsible. The group has been blamed for attacks at the end of last year that forced Sony’s PlayStation Network and Microsoft’s Xbox Live gaming services offline.
eOgxK4iWO3QImage source: Wikimedia Commons President-elect Donald Trump celebrated his election victory at the Ultimate Fighting…
Millions of voters across the US chose to return Donald Trump to the White House…
Donald Trump declares victory in the US election as he addresses jubilant supporters in Florida.…
Stocks around the world are rising as Donald Trump appears to be on the cusp…
Donald Trump has won Pennsylvania, North Carolina and Georgia and taken a lead over Kamala…
Quincy Jones, the celebrated musician and producer who worked with Michael Jackson, Frank Sinatra, Ray…