John Wanamaker the man who invented department stores and price tag in 1870 famously said “Half the money I spend on advertising is wasted, the trouble is, I don't know which half.” More than a century later the proverb still holds true and more so for the internet based advertisements. According to a Mckinsey research internet advertisements going to the wrong audience accounts for $332 billion of wasted resources of which $112 billion is spent in America alone. For any marketer this waste of resources is a night mare. In the following article we will try to look at the various tolls and technique which companies and agencies are using world wide to track their advertisement so that it reach the correct audience.