The problem with your typical signature-based anti-virus software is that it relies on virus signature definitions to do its detection. It works sort of like a vaccine. You get vaccinated against the latest threats, which should protect you should you happen to run into them, and your “vaccinations” come in the form of downloadable updates to your virus signature database. Unfortunately, hundreds of new viruses are released every single day–that’s just way too much for the “vaccination makers” to keep up with. By the time you download the latest virus signatures, they’re already out of date and you’re still left unprotected against the latest threats. That’s where sandboxing comes in.