Internet Security: Cookies & Offline Website Data

Not sure if cookies are a friend or foe? What they are or how they're handled? Check out the topics below.

What are Cookies?

Almost all websites use cookies. Cookies are small pieces of information that are sent to your browser by websites you visit on the internet. They're used to either track visits (monitor website usage), identify you so you don't have to log in every time you visit or to personalise or 'remember' your preferences the next time you visit the site.

When a cookie arrives, your browser saves it to your hard drive. When you return to that site some of the information stored in the cookie will be sent back to the webserver, along with your new request. A cookie can contain information such as a username and password for a site, items that you're purchasing or the addresses of the pages you've looked at.

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What's a Cache?

A browser cache is a group of files, images, objects that have appeared on websites that you've visited and have been saved locally on your computer to speed up browsing.

What's the difference between cookies and files in a browser cache?

Put simply a cookie saves details about browsing sessions that are specific to you and your interaction with a particular website. Whereas the browser cache usually only saves general information about the web pages you've been to so that they load faster the next time you visit them.

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Does Optus use Cookies?

Yes. We do this so you can personalise your service, by saving a user ID for you in a cookie. If your browser does not support cookies or you've got turned them off, this functionality will be unavailable to you. 

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Can I Set My Browser to Reject Cookies?

Yes. All modern browsers provide the ability to block or limit the use of cookies. You will likely find your cookie settings within the tools, preferences or settings menu of your browser. For further assistance customising your privacy and cookie settings, use your browser's help menu.

Keep in mind that if you change your privacy settings it might not affect cookies that are already on your computer. If you want to ensure that all of the cookies on your computer meet your privacy settings, delete them and restart your browser.

After deletion, websites that don't meet your privacy settings won't be able to save cookies on your computer and might not function properly.

When you return to a website that previously had saved cookies on your computer, provided it meets your new settings will again save cookies to your device again.

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Can Cookies Read Information from My Hard Drive?

No. Cookies can only store data that is provided by the server or generated by an explicit user action.

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Where are Cookies Stored?

Cookie data is stored on your hard drive (or if in use in active memory). Cookie formats and file names are different for each browser & operating system. Use your browser's help, settings or preferences menus to find out where they're stored.

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Can Cookies Fill up My Hard Drive?

No. Most browsers have a configurable setting that limits the number of cookies that can be saved on your hard drive  If you exceed this, your least used cookies are discarded to make room for new ones.

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Can Websites Save Information without Cookies?

Yes. Info from the web can be stored in several ways. eg. Website administrators can create a database that tracks and stores data they otherwise would have managed with cookies. Cookies are simply a programming convenience.

Another way that your browser stores information on your computer is by use of a cache. A browser cache is a group of files, images and objects that have been saved to your computer to speed up browsing. Your browser cache can be deleted at any time or preset not to exceed a certain size.

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Can Malicious Sites Read Cookies Used by Another Site?

Cookies are designed to be read only by the site that provides them, not by other sites.

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Can Cookies be Encrypted?

Yes. Programmers can require that cookies be delivered and received only in the context of a secure (Secure Socket Layer - SSL) session. The SSL session handles the actual encryption of cookie data.

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Are Cookies Dangerous?

A cookie is simply a piece of text it's not a program or a plug-in. A cookie alone cannot be used as a virus or access other files on your hard drive.

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Are Cookies a Threat to My Privacy?

A cookie alone cannot read your hard drive to find out who you are, where you live or what your income is. The only way that this kind of information could end up in a cookie is if you provide this information to a website and the site then saves it onto the cookie.

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Can I Delete Cookies, a Cache and Other Offline Website Data?

Yes. Cookies are saved to a simple text file that you can delete as you see fit. Most modern browsers allow you to delete all cookies, each time you shut down your browser, restart your computer or at another configurable point in time. See your browser's help menu for further assistance with customising your cookie and other temporary internet files.

Most browsers have an incognito or private browsing mode. Generally speaking when active, private sessions allow you to browse the web as close to anonymously as possible with the amount of private info and tracking data exchanged between your browser and the internet minimised. Once a private session is ended, usually any cookies, internet history and other forms of website tracking are wiped from the browser and your computer.

For further assistance customising your privacy, cache storage and cookie settings use your internet browser's help menu.

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