Have you ever noticed visiting a website for the first time, then a couple of days later it appears on another site as an advert? This targeted marketing activity is achieved through website tracking. It can be seen in two ways, either very helpful for you as a consumer as you are only shown content or products based on your interests; or manipulative as you are not in control of your online personal privacy.

Read on to discover the various way your online activities are tracked, through HTTP cookies, tracking pixels and IP addresses. Look out for our next instalment where we look at ways you stop this and maintain your online privacy.




A (HTTP) cookie is a small temporary data file a website creates and stores on a website and mobile browsers when a user accesses the website. By recording information about the user’s preferences or past actions, cookies act as a kind of short-term memory for the website, so that the site can tailor the web experience to the end-user. This is generally seen as positive because users then see what they like and do not waste time logging in again for example. 

However, some cookies are invasive and collect data across many websites, allowing certain sites to create ‘behavioural profiles’ of users even if they are just passing by. These profiles can then be used to decide what content or adverts to show the user. This is manipulative, and such use of cookies is what the ePrivacy Directive was designed to regulate. By requiring all websites targeted towards EU citizens to inform and obtain consent from visitors, it aims to comply with GDPR by giving web users more control over their online personal privacy.

IP Address

An Internet Protocol Address is a long number that is assigned to every computer, printer, router or any other device connected to the internet so that the network can uniquely identify the specific interface. This then allows data to be sent and received from a known location to the another over the internet. 

IP addresses are similar to postal addresses in a town or city because the IP address assigns a unique numerical representation to the device, enabling routers to track a user's physical location. An IP address also ensures the correct parties are receiving what is being sent. Akin to the post office which needs a mailing address to deliver a package, a router needs an IP address to deliver to the web address requested.

Tracking Pixels

A tracking pixel is a code snippet which is loaded when a user opens an email or visits a website. It is useful for monitoring user behaviour. With a tracking pixel, advertisers can track conversions and acquire information about visitors on a website (browsing habits, type of ads clicked on etc). This behaviour data helps marketers to send targeted paid ads to users that are likely to be more appealing, using past predictors of consumer interests for online and email marketing.

Browser Fingerprinting

Browser fingerprinting is a method that websites use to collect browser identification points to identify a user and track their online behaviour. 

Browsers actually tell websites a lot of information: time zone, language preference, system fonts, screen resolution, active plugins, and operating system. Using such information collected over time, websites covertly identify users and match unique characteristics of users' browsers to track visitors across websites and build an advertising profile. 

By bulk gathering datasets and storing it on its own servers, browser fingerprinting allows websites to track users without the use of persistent identifiers stored on your device, such as cookies which can be erased manually, subverting the built-in browser mechanisms that allow users to avoid being tracked.

Third-Party Web Tracking/ Ad Serving

Third-party web tracking refers to the practice by which an entity (the tracker), other than the website directly visited by the user, tracks or assists in tracking the user’s visit to the site. It is commonly used by website operators to earn advertising revenue in which another provider pays the platform owner (e.g. Facebook, Google) to display ads, alongside content for users on the online marketplace. 

Third-party ad servers provide an independent counting and tracking system, enabling marketers to quantify click-through-rates (CTR) and impressions in order to generate reports, which help advertisers to determine the ROI for an ad on a particular web page.