If you haven’t done so already, log into your Twitter account, go into Settings and enable the Always use HTTPS option. Click Save.
Facebook has a similar setting.
HTTPS provides reasonable protection against network sniffing, man-in-the-middle attacks, etc. by creating a secure encrypted connection using the SSL/TLS protocol. It is particularly helpful when using websites over Wi-Fi.
Even if you use this feature, make sure your URL starts with HTTPS: in the address bar, like https://twitter.com. Also, all browsers have a lock icon indicator that tells you when you are connected using SSL. (The location of the lock icon varies depending on the browser and version you are using.)
Note that HTTP isn’t just for Twitter and Facebook. Most sites that require a log in will have an HTTPS page. Sometimes it is automatic, like with banks, but commonly it is not. Often, you just need to add the “S”. Also, realize that it isn’t just for logging in. It secures communication for any information. Just understand that if you are not using HTTPS, the data from your computer all the way to the server hosting the website is open for interception.
Good luck and be safe!