Cybercrime is a massive global threat, and U.S. businesses are the No.1 target. For tips and advice about how best to defend against cyberattacks, Network World asked security pros to name their No.1, most valuable security tool.

Many of the experts we interviewed pointed out that there is no silver bullet when it comes to security. Ron Woerner, director of CyberSecurity Studies at Bellevue University put it this way: "There is no 'one and best' security tool. It really depends on the situation, circumstance, and personal preference.