What are website cookies?
Website cookies are text files containing small amounts of data that are created when you arrive on a web page and are stored in your Internet browser automatically. Cookies are used to tailor the experience of using a specific website to a certain user. This information is encrypted, so only the website and your web browser can access it.
Cookies can track which pages you visited while on a site, the IP address and general location of your device, and sometimes login information. This is why some websites will reference where you live, remember your login details from your previous visit, or may suggest returning to a page you've viewed in the past.
There are two main types of Internet cookie:
Session (or 'transient') cookies are only stored for the duration of a web browsing session and are deleted once it's over. These are stored in your browser's temporary memory folder and do not collect personal data.
Session cookies are commonly used by e-commerce websites to pass information from one page to another. For example, session cookies are the reason that the items you place into a shopping bag are retained until you hit checkout – and why they often disappear if you end the session and return later. If you only want to accept session cookies, this can be changed in your browser settings.
A stored or 'persistent' cookie is kept on your hard drive until it expires (this expiration date is set when the cookie is created). Stored cookies collect important information about your activity on a website that makes future visits easier. For example, if accepted, stored cookies can remember your username and password so these details are automatically filled in when you return to a website.
Session cookies are vital to many basic website functions we're now used to, such as online shopping baskets. They act as short-term memory for a website, reminding the site what actions a user has performed on a previous page. Without session cookies, websites would treat every page you access while on a website as a brand-new visitor, causing issues that would impact everything from online shopping to social media.
Stored cookies can make your Internet browsing experience faster and more personalised by remembering personal data you have previously submitted. This means that some websites can tailor your experience based on your previous behaviour, such as offering you the chance to browse products you've already viewed.
What are third-party cookies?
A third-party cookie is a stored cookie that is created by a domain other than the website a user is visiting. Third-party cookies are typically used for advertising purposes, making a note of the pages, domains, or products a user has viewed to influence advertising.
This is the reason some products or pages seem to 'follow' you around. You may see them cropping up on your social media feeds or as banners promoting products, pages, or websites you've previously looked at.
Third-party cookies can be disabled in your browser's settings, preventing third party advertisers accessing things like your search history and browsing habits in order to serve personalised advertisements to you.
More information about cookies can be found on the Information Commissioner's website here.