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The verification codes required for logging into a 2-step enabled account can be generated either using a mobile app - like Authy or Google Authenticator - or you can have them sent to your mobile phone via a text message or a voice call. Once you enable two-factor authentication, a malicious person will not be able to log into your online account even if they know the password - they’ll need access to your mobile phone as well to get in.
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Most big-name web services like Gmail, Microsoft, Evernote, WordPress and Dropbox now support 2-step authentication to improve the security of your online accounts.
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