Similar to Google’s Two-Factor Authentication, users will need to enter a 6 digit code, which is sent by SMS to the users verified mobile phone number to login to Twitter. Â All currently authenticated apps will still function normally with Two-Factor enabled. Â If you need to login to Twitter on another device or app, you will need to visit your Applications Page to generate a temporary password to authorise and authenticate the new app.
Personally I applaud Twitter for taking security seriously; given the number of stories of hacked high profile accounts and the popularity of the service. Â Not toÂ criticizeÂ but maybe hooking into Google’s Authenticator app like Dropbox and other services do would have been a better idea, as SMS does not work with every mobile plan, carrier and network.
Source: Twitter Blog