By Richard Hay for Windows Observer
According to the About.com Wireless/Networking page a hosts file is a list of computer names and their associated IP addresses. Hosts files are used by Microsoft Windows and other network operating systems as an optional means to redirect TCP/IP traffic in special circumstances. These files are not required to use ordinary network and Internet applications.
This file typically sits on your Windows PC without much happening to it. However, there are times when a malicious program may make changes to this file to redirect your attempts to browse to a valid URL and send you to their spam or malware laden website.
In order to get everything working correctly one of the things you will need to do is get the HOSTS file reset to its default state so these unauthorized re-directions do not occur.
This post is excerpted with permission from Windows Observer.