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cookie monsterChances are that you’ve probably heard about cookies – those little pieces of data in your browser on your computer that some say track the sites you visit and compromise your security. There are plenty of rumors going around about them, and in this article, we’ll sort through the myths and truths that exist about how websites use cookies.

While they aren’t the chocolate kind you eat, cookies did cause a quite a security commotion a few years ago and it’s surely worth knowing how they work and what they do on your computer. Cookies are small bits of text data stored in your computer by websites you visit and are organized in a name:value pair along with a separate domain and expiration value. Cookie data is also sent back and forth between certain sites you visit whenever you travel to that site.

Google Search might place a cookie on your computer if you adjust your search preferences with the site for example. If you set your default Google display language to “Ewmew Fudd”, than Google will place a cookie on your computer with the following text:


You can see the word “elmer” and an ID in there, but the rest is not human readable- only data Google uses to store the rest of my search settings and language preferences. Many sites though simply store an ID for your specific computer to keep settings for you when you visit next. But, every time you visit Google again, their site will read this cookie and show you your results in “Ewmew Fudd” language.


how do websites use cookies

Other popular examples where sites store cookies on your computer can be seen in shopping carts, and any site that requires a login or remembers you uniquely somehow during a “session” with that site. Analytics and visitor tracking to monitor how many times you return to a specific site are also another large source of cookies. Also, online ad services such as Google Adsense also store cookies on your computer to display and remember what kind of ads it thinks you might like.

how do websites use cookies

The danger of cookies to some is that they can be used for targeted advertising online, and as I mentioned earlier, sites that use Google Adsense or Doubleclick can keep track of your preferences and ad likings and then target certain types of ads that you specifically like at you as you browse the web (but only on the sites that also use the same ad networks). Different organizations though have different privacy policies, and it is key to understand that targeting is not a threat or danger to your computer; it just makes some people uneasy if they are aware they are being targeted with certain ads.

The Network Advertising Initiative offer a simple page that you can visit here for example that allows you to opt out of some types of targeted advertising from many major ad networks, all on one page.

how do websites use cookies

Most current browsers have an easy-to-use utility to view and remove cookies that sites have stored on your computer. Firefox for example allows you to right-click on a page you are viewing, click on “View Page Info” and then on the “Security” tab. From there in the “Privacy & History” tab, you can click on “View Cookies” to see any cookies that that site has stored on your computer. Chrome also allows you to . While disabling cookies might impair your browsing on many sites, if you’re worried about your cookie security, you can also simply clear out all of your cookies from within your browser’s “Clear Private Data” (Firefox) or “Clear Browsing Data” (Chrome) option. Internet Explorer also allows you to delete your browsing and cookie data every time you exit the browser from Tools > Internet Options.

Do you often clear out your browser history to get rid of cookies or do they sit for months in your computer? Got any additional comment on how websites may use cookies? Share your thoughts below in the comments.

Image Credit : scubadive67

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  1. Mark Anthony
    January 26, 2016 at 8:07 am

    Help me a lot.
    Thanks you.

  2. Buffet
    December 7, 2009 at 6:24 pm

    Thanks Jim!

  3. Travis Berry
    December 6, 2009 at 4:58 pm

    I have my firefox setup to delete everything on close. I don't mind losing remembered passwords as I never check the "remember me" box. Having to use my name and password helps me remember it.

  4. Grant
    December 6, 2009 at 9:17 am

    Flash cookies work a little differently because they can store more than regular cookies can (I think up to 100KB in some cases) and they don't get cleared when you clear your browser's regular cookies or cache. Like regular cookies, they still can watch repeated visits to a site, but that extra threat is that people don't usually think about clearing their flash cookies separately when they clean out their browser cookies.

    You can however view and clear them from a web-based settings manager at Adobe's Website here. Thanks for the comment!

    • Ano
      December 6, 2009 at 4:39 pm

      Thanks for the info : )
      Do you know if there is a simple Firfox addon for clearing flash cookies? I see the one above but it requires settings for individual sites and I would probably do better something a bit simpler.

      Thanks again.

      • Grant
        December 6, 2009 at 5:48 pm

        Sure- you can try something like BetterPrivacy or Objection for Firefox. Thank you for reading and commenting!

      • Jim
        December 6, 2009 at 6:05 pm

        By the way, if you or anyone else is interested, we're beta testing a Firefox addon from PrivacyChoice that only deletes Flash cookies from the targeting firms, so it doesn't interfere with other applications (like online video) where it helps to save your settings and such. If you are interested in trying this out (and taking 5 minutes to confirm that it's working), please drop me a note to Jim at

  5. Ano
    December 6, 2009 at 2:13 am

    Can you explain how Flash cookies work as opposed to regular cookies and how to clear them as well. I may be wrong as I am not technically inclined but I understand Flash cookies have greater security threats than regular cookies and are harder to monitor.


  6. vietvet52
    December 5, 2009 at 12:34 am

    i used to clear them , not anymore kaspersky keeps me safe

  7. Jim
    December 4, 2009 at 4:46 pm

    If you want even more information and choices, try out PrivacyChoice:

    There you can see which ad networks may track your behavior on your favorite sites, and opt-out from all networks, individual networks, or networks with policies that cause you concern. You can also install a simple Firefox add-on to make your choices permanent.

    • Grant
      December 6, 2009 at 9:19 am

      That's an interesting site- neat FireFox addon they have as well. Thanks Jim!

  8. user
    December 4, 2009 at 4:01 pm

    i have set preferences per site, using Opera whenever i clear my private data (including cookies) in one click i know some cookies will remain (i chose which ones)

  9. Mike
    December 4, 2009 at 3:23 pm

    I rarely if ever kill cookies. First off, 99.99% of the time, I dont really care if advertising networks track what I am doing and I if am doing something I dont want to be tracked for, I use Privacy mode ( FF, IE and Chrome all have one ). In privacy mode, no history or cookies are persisted.

    The downside to clearing cookies... you know all those 'remember me' check boxes you have clicked over time? Those are all saved in cookies. I personally despise having to hunt down my bank card every time I log into my online bank.

    To be honest, unless fixing a bug or your tin foil hat is getting a bit too tight, there isnt much harm to be done from cookies. That services like adaware and avg report many as "infections" is more them spreading fear than any actual threat.

    • Nail Moncef
      December 5, 2009 at 3:07 pm

      Imagine that someone installs a third party program on your computer that literally "steals" all your cookies. He would connect with your bank account just by going to the bank's site.
      If I were you, I would clean the cookies of these sites in priority before even getting a threat about a Windows security faille.