You can choose which ads display on your website by carrying out some steps but first, you should know how ad networks choose the ads that are already displayed.
The following are the ways through which an ad network determines relevant ads to display on a website or beside search engine results.
An ad network can only show the ads which it has i.e. ads which have been paid for by advertisers.
For example, website A (which displays Google AdSense ads) is about sand. If Google has no ads for sand, no ads may be displayed. Likewise, if there are no ads related to a search term, none will be displayed in the search engine results. If any ads are still displayed, they may be related in some vague way to the content. However, they could just be ad space fillers.
This situation is commoner when the ads on your web pages are provided by a small ad network or if your content does not have commercial applications.
Ads are targeted to the region of the world from which a visitor is surfing your website. This ensures that only ads which are relevant to that visitor are displayed. For instance, showing ads for surfing products to a user from Mali (a landlocked African country which makes up an area of the Sahara Desert) would be totally irrelevant.
Top-Paying Ads are Displayed First
On ad networks like Google AdSense, advertisers bid to have their ads displayed for particular keywords. Those with the highest bids for a certain keyword will have their ads displayed first and in the most prominent positions.
Google even allows users to choose to see more ads related to their interests by adding those interests to its Ads Preference Manager (www.google.com/ads/preferences). Users who do so will see more AdSense ads related to their interests as they surf the web.
Under contextual advertising, displayed ads match the content of a webpage or search term. Such content is scanned for keywords which are important terms that can be matched to ads. Keyword density is crucial in this form of advertising. It is the amount of times a keyword appears compared to the rest of the words on a webpage. Displayed ads will likely match the keywords that occur most frequently. This is the type of advertising carried out by Google.
This is advertising that is done to directly related websites e.g. ads for cars are placed only on websites dedicated to cars. It differs from contextual advertising where ads are displayed on any webpage as long as a part of its content matches the advert. Ad networks that utilize vertical advertising will always deliver relevant ads to the websites they serve.
Demographics refer to population characteristics such as age, sex, occupation, income, etc. Ads which are displayed are chosen to be relevant to the type of users who visit your website the most. Consequently, your source of visitor traffic influences the ads displayed on your content. For example, if visitors come to your website from “Nanny.com”, then your ads may reflect the type of user expected to visit the former website.
In conclusion, the ads that are ultimately shown on any webpage will usually result from a combination of two or more of the above factors.
Note: Sometimes, the ads on your website may still not match your content. This is common when your website does not get a lot of traffic and thus, the ad network cannot properly utilize any of the above determining factors.
Further Reading: How You Can Choose the Right Ads for Your Website or Web Content. Read this to find out how to get only the right ads to show up on your web content.