Peter W. Singer, director of the Center for 21st Century Security and Intelligence and a senior fellow in the Foreign Policy program at the Brookings Institution, explains how security breaches like the recent ones at Target and Neiman Marcus, happen, who is behind them, and how cybersecurity works and why it matters. He’s co-author of Cybersecurity and Cyberwar: What Everyone Needs to Know, written with Allan Friedman.

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Peter Singer shared some tips for protecting ourselves—and everyone else we're connected to—online.

Strong passwords: Don't use same passwords on all your accounts. Passwords are being sold on the black market. Make your passwords hard to guess (don't use PASSWORD or 12345, which are the most common passwords). Singer also mentioned that security questions like "what is your mother's maiden name?" are easy to look up, so answer that question with the name of your favorite food or your first pet's name.

Don't take hardware from strangers, don't click on links from strangers, and don't open attachments from strangers. Don't click on anything that looks suspicious. And definitely don't click on links offering nude photos of the French First Lady or anyone else.