Twitter has finally introduced a rumored--and much needed--feature: two factor authentication. For those who don't know, two-factor authentication relies on two different pieces of information. Generally, one is a password (something you know) and the other is a code e-mailed or sent to you via text message (something you have).
This technology isn't new. Banks have used it for years with ATM cards requiring a PIN number. After a string of high-profile hackings, including the AP's account, Twitter has introduced this technology for everyone. You are highly encouraged to enable two-factor authentication as soon as you're done reading this article.
You'll be required to register a phone to send codes to. When attempting to log in from an unknown computer, you'll be required to enter a code that is sent via SMS to your registered device.