A "Zero-Day" attack occurs when your computer is infected by a Zero-Day threat û a virus, trojan or spyware which is so new that traditional antivirus programs have no "signature" to identify the threat.

If a threat cannot be identified, it cannot be prevented or contained. Consequently, Zero-Day threats spread very quickly, and pose the greatest risk to the safety of your computer, your online security and the security of your personal data.

A signature is a "digital fingerprint" that traditional antivirus and anti-spyware products use to determine that a virus or spyware has infected a PC or network.

Every threat has a unique fingerprint. A signature will intercept a threat only if the threat has exactly the correct fingerprint.

Because Zero-Day attacks happen faster than traditional antivirus can react. Here is what your traditional signature-based antivirus product must do to protect you against any new threat:

1. Catch the threat.
2. Analyze the threat to understand what it does
3. Write a signature that recognizes the threat.
4. Test the signature to ensure it does not damage your computer.
5. Issue you an update with the new signature. And then…
6. You still have to update your software with the new signature!

It can be days before traditional antivirus companies provide the ôsignature updateö necessary to protect your computer. And traditional signatures cannot protect you if a threat "morphs" to evade the signature.