3aIT Blog

You have probably heard news reports and IT people mentioning cookies in relation to websites, but what exactly are cookies?

Cookies are often referred to as something evil. This isn't necessarily true. In reality, cookies are just text files.

At their most basic, they will contain a unique ID and a website name. Then, the next time you visit that website, it finds that file and knows you've been to the site before, and tailors the website accordingly.

More sophistated cookies can contain all sorts of details including settings that you may have customised for a site, information on how long you have spent on a site, and things you may have put into the website's shopping basket.

Therefore, cookies are generally a good thing, and many modern websites couldn't function without them.

So why are cookies often spoken of in a bad light? This is largely due to third party cookies. These are cookies that are placed on your machine when you're visiting a website that hasn't been placed there by company running the website you are visiting. This is often done via adverts on a website. Once this has been done, it can be used to track a user around the internet. It's easiest to explain this with an example.

  1. You visit example.com. This website places an example.com cookie on your machine.
  2. example.com also has adverts on it. Because this advert isn't directly on the example.com site, but is being served from advert.com (hence third-party), it places an advert.com cookie on your computer
  3. You then visit anotherexamplesite.com. This site also uses ads served from advert.com. The advert code finds the existing cookie on your machine and can use that to track you from one site to another.

Many websites set several of these types of cookies, so a profile of your browsing habits can be quickly established by linking these together.

However, for most people, this is more of a nuisance than something to be too worried about. While it is possible to block cookies entirely, you may find that a lot of the websites that you use may not function correctly if you do so. However, most modern browsers do allow you to block third party cookies, which, if you are particularly concerned about your online privacy, you may find is better approach.

You can find out more about cookies and how to control which cookies your device receives on the ICO website.