Two-factor authentication is probably the best security feature since passwords were invented. Two-factor authentication goes a long way towards protecting one's accounts against being hacked. A password alone, no matter how long or secure, is no longer enough to provide sufficient protection. Social engineering, linked security breaches (http://blog.elcomsoft.com/2013/02/yahoo-dropbox-and-battle-net-hacked-stopping-the-chain-reaction/), leaked passwords, and hacked mailboxes all contribute to the insecurity of password-based protection. Once the intruder gets a hold of someone's password, they can access the account without a fuss. Even worse, they can gain access to other accounts by, for example, using a hacked e-mail address to request password resets on other connected services. Two-factor authentication aims to address this problem.
LinkedIn. Yahoo! Mail. Dropbox. Battle.net. IEEE. Adobe Connect. PayPal. eBay. Twitter. These are just a...