What Are Cookies?

Cookies are pieces of data, normally stored in text files, that websites place on visitors' computers to store a range of information, usually specific to that visitor - or rather the device they are using to view the site - like the browser or mobile phone.

They were created to overcome a limitation in web technology. Web pages are 'stateless' - which means that they have no memory, and cannot easily pass information between each other. So, cookies provide a kind of memory for web pages.

Cookies allow you to login on one page, then move around to other pages and stay logged in. They allow you to set preferences for the display of a page, and for these to be remembered the next time you return to it.

Cookies can also be used to watch the pages you visit between sites, which allows advertisers to build up a picture of your interests. Then when you land on a site that shows one of their adverts - they can tailor it to those interests. This is known as 'behavioural advertising'.

Almost all websites use cookies in some way or another, and every page you visit in those sites writes cookies to your computer and receives them back from it.

Cookies are incredibly useful – they allow modern websites to work the way people have come to expect – with every increasing levels of personalisation and rich interactive functionality.

However, they can also be used to manipulate your web experience in ways you might not expect, or like. It could be to your benefit, or the benefit of someone else – even a business or organisation that you have never had any direct contact with, or perhaps heard of.

It is impossible to tell just by looking at them, whether particular cookies are benefitting you or another party. You have to rely on the website you are visiting to tell you how it uses cookies.

Learn more about the different Types of Cookies, including Supercookies

Other Tracking technologies

Cookies are the most well known and common type of tracking web tracking technologies. However, many websites, advertisers, and analytic tools use other types of technologies to track users or monitor website performance. Below are some examples of other tracking technologies.

Web Beacons and Pixels

A Web beacon, often referred to as a pixel tag, is a clear GIF or web bug, usually no more than 1-pixel x 1-pixel transparent image, that is placed on a website or in an email to monitor the behavior of the user visiting the website or receiving the email. They are often used in combination with cookies.

Web beacons work by sending information along with the request to the web server with the image. For example, when the browser connects to a site with the web beacon, the browser requests the web server to download the image – included in this request can be details such as IP address, type of browser, time of access, or previously set cookies.

Sites generally use web beacons to understand how users travel on the site and use this information to give more personalized content or make browsing more efficient and easier.

If cookies are turned off, web beacons will not be able to track a user, however, they can still be used to account for anonymous visits.


This method of tracking is generally used in conjunction with web beacons. The idea behind fingerprinting is that even with cookies turned off specific information about the user’s device, browser, language, plugins, and other settings can be sufficient to identify a single user.

Local Storage Objects

Local Storage Objects or LSOs are similar to cookies in that they are placed on a visitors browser and used to store information. Much of the same information that is stored in a cookie could be stored in a local storage object.

The main differences between local storage objects and cookies are LSOs do not have an expiration date, they store information in key-value pairs, and they have higher data limits than cookies.

Ultrasound Beacons

Ultrasound Beacons are inaudible signals sent out by TVs, smart phones, or other device to track users outside of the web. For example, a signal could be sent out by a TV advertisement, this signal would be a low frequency that can’t be heard by humans, however, an app in a smartphone could listen for this signal to know that a user has seen a certain TV commercial.

Ultrasound Beacons are also used to connect users in the physical and digital world by having, for example, an ultrasonic beacon installed at a store which can then be used by apps to know if a user has visited a certain store and target ads based on the user’s location.

All About Cookies