Avast Antivirus software is available as a free download for Microsoft Windows and Linux users for their security setups. It includes features like anti-spyware, active monitoring, automatic updates, etc. Avast Antivirus makes it simple to configure your security options to provide the best performance for your system. The latest version of Avast Antivirus has a Web shield feature, which automatically scans, downloads for the presence of viruses and Trojans. Updates are usually set to occur every 4 hours when your system is connected to the internet. It is also a good thing to perform manual updates as well. If your system is not connected to the internet, then you can make manual Avast updates by downloading the latest VPS update on a USB key.
If your computer doesn't have an internet connection, you can make a manual Avast definitions update :