HostsMan

There's a file on your operating system called 'hosts' that stores the IP addresses for the domains of the webpages you want, in order to access those sites more quickly without having to consult any DNS server.

HostsMan is a free Windows application that overwrites your 'hosts' file in order to block the domains that could be serious threats for your PC. It does this by assigning those domains your PC's address, blocking the communication between your PC and the dangerous servers.

However, this strategy can also be used to show you unwanted advertising from webpages, so with this program you will no longer see any (or hardly any) advertisements while you're browsing.

If you have ever used Adblock in Firefox, you can think of HostsMan as something similar, but for your operating system in general.