Paranoid about someone hacking your Instagram account and running amok with Valencia-filtered spam ads for garcinia cambogia? I feel you. I mean, really, who isn't? Fortunately, Instagram just ...

(1) A USB key or app in a smartphone that provides a second authentication mechanism. See two-factor authentication. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction requires ...

The use of two independent mechanisms to verify the identity of a user. Two-factor authentication (2FA) is also called "2-step verification" (2SV). There are four factors: #1. What you know (password, ...

Julia Kagan is a financial/consumer journalist and former senior editor, personal finance, of Investopedia. Toby Walters is a financial writer, investor, and lifelong learner. He has a passion for ...