The Browser Cache – an overview

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Have you ever come across something you’ve never seen or used before, and decided to keep it somewhere close to you so that, if you need it later, you know where to find it and can therefore get it quicker? In technology speak, all the things you put away like this are collectively called your “Cache” (ka-shay); and each time you put something new away like this, it’s known as “caching” it.

Computers work in a similar way. Some programs – and built-in functions of your computer – will save data your computer hasn’t seen before to your computer, so that next time you use the program, it can load the existing data, eliminating the need to create it again, thus speeding up the process.

A long time ago, Microsoft saw fit to bring this whole Cache paradigm to the Internet (whether they invented it or not is a point of debate, but certainly their version set the standard), introducing to its browser a function that downloaded things it hadn’t seen before, so that the next time you visited a website it would load quicker. Other browsers followed suit, and for many years now a cache has been a standard part of any half-decent internet browser. While Microsoft refer to files saved in this way as “Temporary Internet Files”, most other browsers simply call it the “Browser Cache”.


When you visit a web page you’ve never visited before, your internet browser takes a look at the website and notes down the information on it, unless it’s a script or the website has told the browser to ignore it. Then, as the website appears on your screen, the browser starts saving information about the website – such as the text, images, layout and so on – to a specially made folder on your computer.

When you visit the same page again at a later date, your browser first looks at the page as it is now, and compares each part of the page to what it has remembered in your cache. If it notices some of the information about the site is exactly the same to some of the information stored in the cache, instead of asking the website to provide the information when it loads the web page, it will get it from your computer instead; so only NEW information is downloaded from the actual website itself. This speeds up loading the page and uses up less of your bandwidth. Also, if the browser has saved some information about the website before that it notices has now changed, it will get rid of the old data from the cache and save the new data. Thus, as long as a web page doesn’t update too often, your computer can keep what it knows about a page up-to-date, and save time the next time you visit the same page.

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