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7c8f75b5474321009db4b5b08b9a71b5

Summary
Number:	KB0000007	Workflow:	published
Knowledge Base:	IT	Published:	2014-09-10
Category:	IT / FAQ
Author:	Wayne Webb
Valid to:	2100-01-01
Short description:	What is a cookie?\t\t

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What is a cookie?

Cookies are messages that web servers pass to your web browser when you visit Internet sites. Your browser stores each message in a small file, called cookie.txt. When you request another page from the server, your browser sends the cookie back to the server. These files typically contain information about your visit to the web page, as well as any information you've volunteered, such as your name and interests.

Examples of cookies

Cookies are most commonly used to track web site activity. When you visit some sites, the server gives you a cookie that acts as your identification card. Upon each return visit to that site, your browser passes that cookie back to the server. In this way, a web server can gather information about which web pages are used the most, and which pages are gathering the most repeat hits.

Cookies are also used for online shopping. Online stores often use cookies that record any personal information you enter, as well as any items in your electronic shopping cart, so that you don't need to re-enter this information each time you visit the site.

Servers can use cookies to provide personalized web pages. When you select preferences at a site that uses this option, the server places the information in a cookie. When you return, the server uses the information in the cookie to create a customized page for you.

Security concerns

Only the web site that creates a cookie can read it, so other servers do not have access to your information. Additionally, web servers can use only information that you provide or choices that you make while visiting the web site as content in cookies.

Webmasters have always been able to track access to their sites, but cookies make it easier to do so. In some cases, cookies come not from the site you're visiting, but from advertising companies that manage the banner ads for a set of sites. These advertising companies can develop detailed profiles of the people who select ads across their customers' sites.

Accepting a cookie does not give a server access to your computer or any of your personal information (except for any information that you may have purposely given, as with online shopping). Also, it is not possible to execute code from a cookie, and not possible to use a cookie to deliver a virus.

How do I clear my web browser's cache, cookies, and history?

Notes:

• If you don't see instructions below for your specific version or browser, search your browser's Help menu for "clear cache". If you're unsure what browser version you're using, from the Help menu, select About [browser name]. InInternet Explorer and Firefox, if you don't see the menu bar, press Alt.
  
  
• When troubleshooting issues with any web site, after clearing your browser's cache and cookies, exit your browser completely before attempting to access the site again. In Windows, close all your browser windows; in Mac OS X, quit (Command-q) your browser.

Android

1. Start your browser.
2. Tap Menu, and then tap More.
3. Select Settings.
4. Under "Privacy settings", select Clear cache, Clear history, or Clear all cookie data as appropriate, and then tap OK to accept (or Cancel to cancel) the deletion.

Chrome

1. In the browser bar, enter:
   chrome://settings/clearBrowserData
2. Select the items you want to clear (e.g., Clear browsing history, Clear download history, Empty the cache, Delete cookies and other site and plug-in data).
   From the Obliterate the following items from: drop-down menu, you can choose the period of time for which you want to clear cached information. To clear your entire cache, select the beginning of time.
3. Click Clear browsing data.

Firefox

1. From the Tools or History menu, select Clear Recent History.
   If the menu bar is hidden, press Alt to make it visible.
2. From the Time range to clear: drop-down menu, select the desired range; to clear your entire cache, select Everything.
3. Click the down arrow next to "Details" to choose which elements of the history to clear. Click Clear Now.

Internet Explorer 8 and higher

1. From the Tools or Safety menu, select Delete browsing history....
   If the menu bar is hidden, press Alt to make it visible.
2. Deselect Preserve Favorites website data, and select:
   
   
   • Temporary Internet files or Temporary Internet files and website files
   • Cookies or Cookies and website data
   • History
   
   
3. Click Delete.

Internet Explorer 7

1. From the Tools menu in the upper right, select Delete Browsing History....
2. To delete your cache, click Delete files....
   To delete your cookies, click Delete cookies....
   To delete your history, click Delete history....
3. Click Close, and then click OK to exit.

Mobile Safari for iOS (iPhone, iPod touch, iPad)

To clear cache and cookies:

1. From the home screen, tap Settings, and then tap Safari.
2. At the bottom of Safari's settings screen, tap Clear cookies and data, orClear Cookies and Clear Cache. Confirm when prompted.

To clear history:

1. From the home screen, tap Safari.
2. At the bottom of the screen, tap the Bookmarks icon.
3. In the lower left, tap Clear.
4. Tap Clear History.

Opera

1. From the Opera menu, select Settings, and then Delete Private Data....
2. In the dialog box that opens, select the items you want to clear, and then clickDelete.

Safari

1. From the Safari menu, select Reset Safari....
2. From the menu, select the items you want to reset, and then click Reset. As of Safari 5.1, Remove all website data covers both cookies and cache.