Example - the following entry 127.0.0.1 ad.doubleclick.net blocks all files supplied by that DoubleClick Server to the web page you are viewing. This also prevents the server from tracking your movements. Why? ... because in certain cases "Ad Servers" like Doubleclick (and many others) will try silently to open a separate connection on the webpage you are viewing, record your movements then follow you to additional sites you may visit.AND IT ADDS TIME TO THE PAGE LOADING TIME...
MVPS HOSTS now includes most major parasites, hijackers and unwanted Adware/Spyware programs!
you can use the custom host file located here...
read down the page until you find the hosts.zip download
special instructions for windows 7 here ...
I've both used it and recommended it for at least three years
you will notice a faster loading of web pages because it does not have to connect and download those ad's