Facebook this week will begin turning on secure browsing be default for its millions of users in North America. The change will make HTTPS the default connection option for all Facebook sessions for those users. Facebook users have had the option of turning on HTTPS since early 2011 when the company reacted to attention surrounding the Firesheep attacks. The technology is by no means a cure-all for Web-based attacks, however, as there have been demonstrations of attacks that enable third parties to snoop on encrypted traffic and grab valuable data.
Source: https://threatpost.com/facebook-enabling-https-default-north-american-users-111912/77226/