There is no third party advertising on my site.
Unfortunately there are organisations that are attempting to inject so-called 'targetted' advertising as people browse the web. By doing this they are trying to make money out of other peoples work (website owners).
They try to pass this off as beneficial to the users, claiming that they will give you warnings about dangerous sites and you will only see advertisements that are relevant to you, but to do that they have to make quite a detailed examination of your web browsing habits - without telling you what information they are storing and who they might pass it on to.
They are effectively defacing a site owners pages and therefore in breach of their copyright. They are also putting you, the viewer at risk, as you can no longer be confident of the source of anything you see when browsing a site. If your ISP allows a third party to inject such information, there is no way for you to tell if anyone else is doing so.
Placing targetted advertising on top of a commercial website is a serious affront. It means that the website owners are now effectively advertising their competitors, in a way that many viewers are likely to mistake as an endorsement for these products and services. What is more, the website owners don't even get to see which advertisments are defacing their site.
For personal site owners, there is a similar issue. Most people have quite strong beliefs and moral codes. There is now a very real possibility of great insult where an advertisement goes directly against the site owners statements and beliefs. Can you imagine the grief that would be caused where such an advertisement prompts an outraged viewer to contact the site owner and accuse them of hypocracy?
A few countries have woken up to this abuse and made the practice illegal, but many have not. If you see such advertising that appears to be from my site, please complain to your ISP.