How To block website using windows host file

 Hosts file is a list of web addresses. When you type an address on  browser, it checks for instructions on the HOSTS file; if no record about a website is found, it opens a website for you. Otherwise, it opens a website from an IP address defined on the HOSTS file. If the address leads to 127.0.0.1, you won’t be able to access the website, because 127.0.0.1 is an IP address of your computer.

Find and open the HOSTS file

Windows XP, Vista and Windows 7
C:\WINDOWS\system32\drivers\etc

Then open hosts file using Notepad 

The entry must have two parts: an IP address and the address of the website you want to block. Choose 127.0.0.1 as an IP address, leave a space and then type the address of the unwonted  website. 

( example ) 127.0.0.1    example.com