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What are Cookies?

What are Cookies?. How did they do that?. Sites that know you. Just a few common examples: my.yahoo.com www.amazon.com Each time I return to these sites, they remember who I am. Yahoo remembers my news, bookmarks, etc.

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What are Cookies?

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  1. What are Cookies? Cookies

  2. How did they do that? Cookies

  3. Sites that know you... • Just a few common examples: • my.yahoo.com • www.amazon.com • Each time I return to these sites, they remember who I am. • Yahoo remembers my news, bookmarks, etc. • Amazon.com remembers what books I have browsed and makes recommendations. • How do they do that? Cookies

  4. What is a Cookie? • Small piece of data generated by a web server, stored on the client’s hard drive. • Controversial, as it enables web sites to track web users and their habits (more later…) Cookies

  5. Tracking Unique Visitors • Step 1: Person A requests home page for amazon.com • Step 2: amazon.com Web Server generates a new unique ID. • Step 3: Server returns home page plus a cookie set to the unique ID. • Step 4: Each time Person A returns to amazon.com, the browser automatically sends the cookie along with web page requested. Cookies

  6. Cookie Conversation Give me the home page! Browser Server Here’s the home page plus a cookie. Now, give me the news page (cookie is sent automatically) I’ve seen you before… Here’s the news page. Cookies

  7. Cookie Notes • Created in 1994 for Netscape 1.1 • Cookies cannot be larger than 4K • No domain (netscape.com, microsoft.com) can have more than 20 cookies. • Cookies stay on your machine until: • they automatically expire • they are explicitly deleted • Cookies work the same on all browsers. No cross-browser problems here! Cookies

  8. Magical Cookies • The term cookie comes from an old programming hack, called Magical Cookies. • If a programmer couldn’t make two parts of a program communicate, she would create a “magical cookie”, a small text file containing data to transfer between program parts. Cookies

  9. Why use Cookies? • Tracking unique visitors • Creating personalized web sites • Shopping Carts • Tracking users across your site: • e.g. do users that visit your sports news page also visit your sports store? Cookies

  10. Cookie Anatomy Cookies

  11. Cookie Anatomy • Version 0 specifies six cookie parts: • Name • Domain • Path • Expires • Secure Cookies

  12. Managing Cookies Cookies

  13. In Netscape 4.0 and above • Netscape provides several cookie options • Accept all cookies • Accept only cookies that get sent back to the originating server (used to block third party ads) • Disable cookies • Warn me before accepting a cookie. • Menu Tab: Edit -> Preferences -> Advanced Cookies

  14. Cookies

  15. In Internet Explorer • Provides several options: • Prompt before accepting cookies • Disable all cookie use • Always accept cookies • IE 5.0: • Menu: Tools -> Internet Options -> Security -> Custom Level Cookies

  16. Cookies

  17. Netscape Cookie Files • Netscape stores all cookies within a cookies.txt file. • Columns: • Domain name • HTTP Header: • TRUE: cookie was set by an HTTP header • FALSE: cookie was set by JavaScript • Path • Secure • Name • Value • Let’s take a look... Cookies

  18. IE Cookie Files • Cookie files are stored within a cookies directory under windows: C:\windows\cookies • Each cookie gets its own name. • Let’s take a look... Cookies

  19. Cookie Block Software • Cookie Central has pointers to lots of cookie blocking software. • Cookie Pal • Cookie Crusher • Cookie Cruncher • etc. Cookies

  20. Privacy • Lets look at this website that provide informmation such as address, phone, email, and more: • www.411.com • Yahoo: • http://people.yahoo.com/ • http://find.intelius.com/search-name.php?ReportType=8& Cookies

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