The browser cache appears in more answers than questions, but often causes even more questions.
Even while following instructions to empty the cache, many people aren’t clear on what this piece of magic really is, or why clearing the cache does anything at all.
Let’s review what the browser cache is and why it exists. I’ll also point you to steps to clear it in Edge, Internet Explorer, Firefox, and Chrome, and try to dream up some reasons why that sometimes helps.
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The browser cache
The cache exists because of a basic assumption made by browser designers: the internet is slow.
More accurately, your internet connection is slower than your computer.
It’s faster to get something from your hard disk than it is to get it from the internet. Even with today’s internet speeds, that still holds true.
Browser designers noticed that most websites have many of the same elements on multiple pages. For example, if you look at this page, you’ll see the Ask Leo! logo at the top. It’s actually at the top of every page on this site. So the thinking was, why download the same logo over and over for every page? Why not just download it once and then keep a copy so we can display it again without downloading it every time?
That’s the browser cache. It’s nothing more than a place on your hard disk where the browser keeps things it downloaded once in case they’re needed again.
The very first time you visit any page on this site, the browser downloads the logo, and several other items, into the cache, and then displays it as part of the page you’re viewing. For each additional page you visit, as long as the same logo is displayed, it doesn’t need to be downloaded again — it’s already on your hard disk.
The cache has a size limit, which you can usually configure. When the cache gets full, the items in it that haven’t been used in a while are discarded to make space for items you’re using now.
Naturally, there’s more to it than that. For example, there are ways for me to update the logo on my site and have that override whatever is in your cache, so what you see is always up-to-date. But by and large, that’s all it is: a place to keep things locally so you don’t have to download the same things over and over again.
And it’s all transparent to you.
Until something breaks.
Clearing the cache
Clearing the cache just means emptying it, so the next time you display a webpage, everything must be downloaded anew.
For reasons I can’t explain — other than by saying “stuff happens” — the cache sometimes get confused. This seems to happen to all browsers and at random times. You’ll see partially loaded or badly formatted webpages, pages that should update but don’t, incomplete pictures, or, in some cases, the wrong picture in the wrong place.
It’s not always a caching problem, but because it happens often enough, “clear your browser cache” is one of the first diagnostic steps you’ll hear from people like me.
I’ve put together instructions for the four most popular browsers.
- How Do I Clear The Browser Cache in Microsoft Internet Explorer (IE)?
- How Do I Clear The Browser Cache in Mozilla Firefox?
- How Do I Clear The Browser Cache in Google Chrome?
- How Do I Clear The Browser Cache in Microsoft Edge?
An empty browser cache
Your browser cache is empty – so what?
An empty cache means there’s no confusion. As you visit webpages hereafter, the browser will download fresh copies of everything you see on each page. You’ve simply forced your browser to rebuild its cache from scratch as it loads or re-loads pages. Any cache-related issues should be cleared up.
Until the next time.