On the internet it’s possible to get news, pictures, music, video and all kinds of other information legally and without having to pay for it.

This is made possible by advertising – for example, when you read an article on this website, it appears on your screen along with a couple of advertisements that help us to pay for the site.

With new technology, though, companies can monitor what people do online and send them advertising that is appropriate to them, based on their habits. This ‘behavioural advertising’ has caused a huge amount of controversy – but is it anything to be afraid of?

Everyone’s a winner
The promise of behavioural advertising is that everybody wins. The advertisers get to show more appropriate adverts, so there’s a greater likelihood that they’ll be clicked, making them more effective. The websites stand to make more money from the adverts, which increases their profits. Internet users, meanwhile, don’t get bothered with adverts that aren’t relevant, instead receiving more useful offers and information as well as free access to the site.

Internet Service Providers (ISPs) also stand to benefit. Some behavioural advertising systems, such as the Webwise system developed by Phorm, require special software or equipment to be installed at the ISP, allowing these companies to make money by striking deals with the advertising companies.

So if every party stands to gain from behavioural advertising, why has it caused so much controversy? There are two key issues that cause disagreement: whether users should be concerned about people keeping track of things they do online, and whether they have any choice in the matter.

Cookie monsters
It’s important to note that the idea of websites tracking where you surf online is not new. For years websites have used a technology called cookies to keep track of what their users do. These can track how often you visit a site, or which pages you view, but they are normally limited to a single website or a group of sites owned by one company. They’re largely innocuous, although some security software will classify them as harmful and remove them, and it’s easy to delete or block any cookies you don’t want.

Cookies should not be confused with adware – software that is installed on your PC and snoops on what you’re up to in order to display ads. This can normally be removed by internet security software. In general, though, both cookies and adware can be easily removed from your PC if you wish, leaving you in full control.

Your browsing can also be tracked by websites such as search engines. Google, for instance, monitors the words and phrases you search for, and uses this to display relevant adverts to the right of the search results.

This kind of technology isn’t reserved to search pages, either: when the Google Mail service was set up in 2004 the company made waves by announcing that it would subsidise it through targeted advertising. It reads emails that are sent or received by Google Mail addresses and displays advertising appropriate to the emails’ content.

If you have a Google Mail account it’s easy to see this working – log in and read an email, and you will usually see an advertisement on the page that bears some relevance to your message. If you’re emailing friends about booking a holiday, for instance, you may see adverts from travel companies.

Google promises that this is all done anonymously and that individual users aren’t being tracked but, in any case, with search engines users have a choice – if you don’t like the idea of Google Mail’s computers reading your messages, you’re free to find a different email service.