Definition
Contextual targeting is a form of targeting that the ad servers use to target a user for showing ad units based on the context of the page they are viewing. This means that if the user is viewing a page with sports content on it, the ad that will be displayed on that page will be sports related. Targeting might be available at a finer level of granularity as well. An ad server might be able to target the ad based not only on the fact that it is about sports, but about the fact that it is about Super Bowl which falls under NFL which falls under Sports. Such type of targeting could be very valuable for an advertiser and they might be willing to pay top dollars for it.
An Example
Here is an example to illustrate the working of contextual targeting. Suppose you visit a news site and browse to its finance section. When you request a page from the finance section of the site, the page might have JavaScript embedded on it that might make a request to an ad server with some meta data information about the context of the page. This information could be about the URL of the page, its content, the section of the site where it is at etc. On the ad server there are targeting rules and associations that let an advertiser target their ad units to the various contextual information passed by the embedded JavaScript. There would be a targeting rule on the ad server, for example, for showing e-trade ads when the page is about personal finance or investing. When the JavaScript submits to the ad server information about the context of the page – in this case personal finance, an e-trade ad will show up.
Concerns
When Google launched contextual ads in gmail there was a big uproar about privacy. If you got an email from your friend about plans to watch super bowl at his place and right beside it was an ad to buy cheap super bowl tickets, it could freak you out. Everybody thought Google was reading their emails. If Google wants it can read your emails, but in this case there were not. All they were doing was passing the contextual information of the email back to their servers which were returning back the best possible ad for the context. There are other companies, like Entrieva or Context Web that do similar targeting if you were on a public page like a news site or some other publisher sites. It just seems very intrusive when you have logged into something and you think everything is very private when you see an ad which ‘knows’ what you are looking at. If Google is providing mail service to you just like Yahoo , MSN and AOL they have the capability of reading your mails anyways so why freak out if you see targeted ads based on the context of the mail. These technologies are the onset of next age of advertising on the Internet and we should embrace them. It is because of these forms of online advertising that we have free services on the web.
Market
Some of the companies that provide contextual targeting are:
