Explained: Cached data and website cookies

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Online jargon can be confusing. Even commonly used terms like ‘cache’ and ‘cookies’ might not be clear. So, what do they mean? Whether you browse the web on your mobile or desktop, you’ll come across these types of files at some point. Here we explain everything there is to know about cache and cookies:

What does cache mean?

In basic terms ‘cache’ and ‘cached data’ refer to information from a website or app that’s stored on your computer, smartphone or tablet. This data is kept on your device, so it’s readily available the next time you revisit.

Your device remembers every website you visit and downloads temporary Internet files (such as images) to speed up site loading time. Because the data is stored locally on your computer, it’ll be much faster to load and makes your browsing experience better.

What are cookies?

Cookies (of the non-baking kind) are small files that are downloaded to your device whenever you browse a site, storing previous activity or user preferences. The purpose of website cookies is to create a more personalised journey.

Items left in your shopping basket, targeted marketing, or being automatically logged into your favourite website are all examples of cookies at work!

There are three types of cookies:

• Session cookies (used by online shops and expire when your browser is closed)
• Permanent cookies (stay working even when you’ve closed your browser)
• Third-party cookies (collected by third parties for research into demographics and behaviour)

Find out more about cookies in our 'what is a cookie' guide.

What is cache memory?

Cache memory (also known as CPU memory) is stored on your desktop, tablet or smartphone. When websites are cached, space is taken up on your device – with apps easily occupying more than a gigabyte of memory. For websites you regularly visit and apps you use often, caching has incredible benefits, but for a site you visit just once, it can be a waste of valuable disk space.

What does 'clear cache' mean?

You may hear people talking about “clearing their cache”. The benefits to caching, as explained earlier, is that you can enjoy faster and more personalised browsing. The downside is that it takes up space on your machine and can even leave you vulnerable to security risks (due to storing sensitive data). Because of this, it’s recommended that you clear your cache every once in a while.

Instructions for clearing your cache and cookies will vary between browsers as well as different mobile operating systems (e.g. Android or Apple), so follow our helpful guide to clearing cache and cookies to ensure you have everything covered.

Clearing your cache is also often a necessary step for broadband speed testing and could help to improve the battery life of your mobile.