Skill Level Appropriate for all
- [Instructor] As we browse the web, our web browser builds up a series of files and little pieces of information that are intended to make the browsing experience smoother, faster, and easier. Generally speaking, these are called cache and cookies. The cache stores information that sites use to display pages; things like images, scripts, and other files that it makes sense to send once and then store on your computer in case they're needed again. There's no reason, for example, for a website to send its logo the first time you look at a page and then send it again for every page that you browse to that has the same logo.
The logo is loaded from cache every time a site asks to display it. This makes for a faster browsing experience because the file is coming from your computer instead of from the web, and it also saves on bandwidth, for both the client and the site host. Even fairly simple web pages are made up of many many files, and though they're usually small, repeatedly transferring even small files over and over again adds up to a lot of traffic, especially for the web hosts. Most files stored in cache, this way, have expiration dates, so every now and again, a new copy will be downloaded, but they won't be downloaded every single time they're used.
Caching files improves the browsing experience but it can also reveal information about what sites you've visited. The cache is just a bunch of files on your computer, usually deep in a library folder. But, the point is, those files can still be viewed by someone with access to your computer. So, it can be a good idea to clear out the cache now and then if you're concerned about that. Clearing the cache is also a common troubleshooting technique if a site isn't working quite right. It could be that there's an old file in cache that hasn't expired yet, and it's being called up instead of being replaced by a newer version.
Another type of information that a browser stores are called cookies. These pieces of data store information about you for various sites. Cookies can store user preferences, like language and location, and can also store information about a user account, like your access token for a site you often log into, so you don't have to login every time you visit the page. They don't store everything a site knows about you, like your shipping address or profile photo. Those are stored in the sites database. Instead, cookies hold little pieces of information to make your browsing smoother.
Like the cache, cookies can improve the browsing experience, but because they store information about you, they can also be a security risk. Some cookies can be read by sites that didn't create them. That's one way, for example, a site might know about products or brands you've looked at, and can use that information to target advertising to you, or know that you're a Facebook user, or an Amazon shopper, or something like that. It's not the only way advertisers get information, but it's one avenue. Other cookies are created by services like ad networks, social networks, and analytics packages, when their functionality is included by the site's owner.
These are called third-party cookies. As you browse the web, the browser keeps a list of the pages you've visited. This makes it easy to get back to a previous place you've visited before, either the same day or weeks or months later, and, like other information the browser collects, this can reveal personal information to some degree, so it's good to know that it's there and that it can be cleared out. We'll see how to do that in a moment. The browser can also store login information, like a password manager does, and it can store payment information, like credit card numbers and billing and shipping addresses.
As with the other information the browser stores, keeping this information ready at hand can make logging into, and purchasing things from, sites a lot easier. And, you can manage what's stored there, to remove information that you don't want stored, or to make changes, if need be. Let's take a look at where to find and clear cache, cookies, history, and other stored information, in Firefox on Windows. If you use a different browser, you'll need to explore the settings a little bit to find these options. Here, in my blank browser, I can click this icon and choose History, and I can see that earlier today I was browsing about William Shakespeare, visiting Wikipedia, looking at Amazon, and so on.
If this were my computer, I would be fine with that but if it's a shared computer, I might want to get rid of my history. To clear out that information, I'll open up this menu and choose Options. The, under Privacy & Security, I'll scroll down a little bit and find an area where I can clear out different kinds of information. The first one is Cookies and Site Data. I can click Manage Data to see what's stored, and I can click Clear Data to remove all of the information in my cache.
Further down, I can see what stored information for forms and passwords, the browser has. If I click on Saved Logins, I can see that I have three accounts for different websites. I could choose to show the passwords for these, but I won't do that right now. If I needed to, I could edit some of this information, or I can remove individual items, or everything. I'll remove all of my stored passwords, here. And, below that, there's an option to clear my history.
Here, in Firefox, I can choose to remove history from the last hour, two hours, only today, or everything. I'll choose everything and make sure that everything here is selected. This will not only remove my browsing history, but also cookies, cache, and form and search history. I'll press Clear Now to get rid of all of my personal information. Now, when I look at my history, I can see that it's empty. If you want to browse without having to clear out your stored information all the time, many browsers offer a private browsing mode, which doesn't store history, cache, or cookies, for the time that you are using that private window.
Here, in Firefox, I can open a private browsing window by opening the menu and choosing New Private Window. Browsers generally collect a lot of information as we browse and it's important to know, both that the information exists and how to clear it out when it's not needed.