We can block websites in windows by modifying HOSTS file.
What is HOSTS file?
One of the lesser known, but important files included with Windows is the hosts file.
It's
a simple text file without any file extension that was designed to map
or override IP addresses before accessing a domain name server.
i.e
when you enter a domain name (eg:www.google.com), your browser searches
for the IP address of www.google.com in your HOSTS file before
searching it in the DNS server.
Procedure:
step 1)open your notepad with admin rights as shown below.
step2)now goto file and click on "open" and then navigate to C:\windows\system32\drivers\etc
step3)Now change your extension to "all files" in the notepad.
you will see HOSTS file and open it.
It will look like
step4)add the following lines in the HOSTS file as shown in the figure.
127.0.0.1 www.google.com
127.0.0.1 google.com
step5)save it. and open your browser. Now type www.google.com
It will not be opened.
cheers.