CNet: Tumblr has begun to catch up with modern security standards by activating SSL on Monday. There’s a catch, though: You have to enable SSL on Tumblr manually.
If you’re not familiar, Secure Sockets Layer, or SSL, allows for the data being transmitted from the Tumblr server to your computer to be encrypted. SSL decreases the likelihood of casually eavesdropping on people who visit sites with it enabled.