Each field is separated by white space (Tabs are often preferred for historical reasons, but spaces are also used). The Hosts file contains lines of text consisting of an IP address in the first text field followed by one or more host names. The hosts file is one of several system resources that address network nodes in a computer network and is a common part of an operating system's IP implementation. The Hosts file is used by the operating system to map human-friendly hostnames to numerical Internet Protocol (IP) addresses which identify and locate a host in an IP network. How to Block Websites using Hosts File in Windows
