What are browser cookies?
Cookies (as well as being a delicious treat) are typically small files that contain code that websites store on your computer - a bit like a passport. Every time you visit the website, the cookie file is read and updated based on your activity. Cookies can be used for a number of purposes, such as personalising your visit to a website by saving certain preferences about you, or to track your behaviour to help the website owner understand what is and isn't working well on their website. On May 25th, 2011, a set of 'Privacy and Electronic Communications Regulations' were proposed in the UK that would require all websites to ask for your consent to store information about you in a 'cookie' by May 2012.
A great example of how cookies work can be found in the code behind a shopping cart on a retail website. Without a cookie file to record the products in your basket, every time you refresh the page or navigate to a different page you would lose the contents of your basket. Cookies can also remember your login details on websites when you tick the "remember me" check box, as well as show you recommended products while you’re shopping online by telling the website which products you've looked at previously. Websites can only access data from cookies that relate to themselves. This helps to protect your privacy and prevent websites from snooping in on what you might be doing on other sites, or accessing personal details you haven't provided to them.
For the most part, cookies are a very practical and important part of an enjoyable browsing experience, however there are some things it's worth being aware of too. Since cookie files can store your login details, you should be wary of what data you agree to store on public computers, since other people could potentially log in using your saved details or find out other personal information about you. Ensuring you only save details when on private devices will lower this risk.
Cookies can also be used to tell advertisers which websites you’ve visited so they can tailor their adverts to you, ensuring they reflect products and services that appear relevant to you. You may have noticed this happening after you’ve looked at something online and then seen ads relating to it on a different website. In this instance, a cookie from the advertisers has been passed from one site to the next to target you more effectively. You can usually opt out of these kinds of cookies to prevent this from happening, following which you should see generic advertisements instead.
Cookies can be managed from within your web browser, so it's worth checking if there are cookies storing data for websites you don’t trust, or want to be forgotten from. You can visit these links to learn how to remove cookies from Chrome, Firefox, Edge and Safari. It’s worth noting that if you clear your cookies, you will be logged out of all websites and any preferences you’ve set on them may be forgotten.