If you have Google AdSense on your site, sometimes you see ads there that you don't want. Perhaps you don't want your readers to visit those sites or perhaps you don't think they are appropriate. Whatever your reason, it is possible to prevent them from displaying on your page.
Presumably a lot of you already know how to do this, but for those of you who don't, it's quite simple.
First of all, you need to know the URLs of those sites. Now, according to the Terms of Service for AdSense you aren't allowed to click on the ads on your own page to find out. What you have to do is download the AdSense Preview Tool. This can be done very quickly by going here.
Once you have downloaded and installed the Preview Tool, you go to your page and right-click. Google AdSense Preview Tool will now show up on the menu. Click this and you will see a list of ads.
Check the ads you don't want and then click on Show Selected URLs. This will give you the URLs.
Go to your AdSense account and click on AdSense Setup. Then click on Competitive Ad Filter. Under AdSense for Content filters enter the URls of the ads you want blocked and then click Save Changes.
That's it! It may take a few hours for it to take effect, but those ads will no longer appear on your page.
One thing I would like to point out is that after I had downloaded the Preview Tool, it only showed up using Internet Explorer and not with Firefox. This is something I need to check out, but you should be aware of that.