Starting today, Gmail will always use an encrypted HTTPS connection when you check or send email.
Gmail has supported HTTPS since the day it launched, and in 2010 Google made HTTPS the default. Today's change means that no one can listen in on your messages as they go back and forth between you and Gmail's servers - no matter if you're using public WiFi or logging in from your computer, phone or tablet.
In addition, every single email message you send or receive is encrypted while moving internally. This ensures that your messages are safe not only when they move between you and Gmail's servers, but also as they move between Google's data centers.