Avast Free Antivirus is a popular free antivirus for Windows. It enables users to protect your computer from a possible virus infection or other malware threat. Besides efficient protection against viruses and spyware, Avast Free Antivirus features eight real-time shields that keep your system safe from online threats in various areas: web browsing, email, instant messaging, P2P and more – plus the two new Script and Behavior Shields. The eight shields in Avast Free Antivirus can be enabled or disabled individually, and have their own settings.