Clear Cache and Cookies

The browser cache appears in more answers than questions, but it often causes even more questions.

Even when 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 the browser cache, what it is and why it exists. Along the way, we’ll review the steps to clear it in Internet Explorer, Firefox, and Chrome and try to dream up some reasons why that sometimes helps.

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.

What that means is that it’s faster to get something from your hard disk than it is to get it from the internet. Even with today’s faster internet speeds, that still holds very true.

Browser designers noticed that most web sites had 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 for every page? Why not just download it once and then keep it so we can use it again?

Cache That’s what the browser cache is for. The cache is nothing more than a place on your hard disk where the browser keeps things that it downloaded once in case they’re needed again.

When you first visit a page on this site, the browser downloads the logo into the cache, and then displays it on the page you’re viewing. For each additional page you visit, the logo doesn’t need to be downloaded again; as long as the same logo is displayed, 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 more space.

Naturally, there’s a little 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, of course.


Clearing the cache

Clearing the cache just means emptying it, so that the next time you display a web page everything must be downloaded anew.

For reasons I simply can’t explain – other than by saying “stuff happens” – the cache sometimes get confused. This seems to happen to most all browsers and at random times. What you’ll see are partially loaded or badly formatted web pages, 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 often one of the first diagnostic steps you’ll hear from people like me.
Here’s how.


Clearing Internet Explorer’s cache

Examples are Internet Explorer 11; older versions are similar.

Click the Tools menu (or click the gear icon in the upper right of the Internet Explorer window), and then the Internet Options menu item. In the resulting dialog box, under Browsing History, click the Delete… button.



In the resulting Delete Browsing History dialog, it’s the Temporary Internet files and website files item that specifically refers to the browser cache, so check it. You can select or deselect other items as you see fit.

Once you’ve done so, click the Delete button.



Your browser cache is now empty.

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