What are Cookies

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What are Cookies?
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How did they do that?
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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?

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What is a Cookie?

• Small piece of data generated by a web server,
  stored on the clients hard drive.
• Controversial, as it enables web sites to track
  web users and their habits (more later)

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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.

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Cookie Conversation
Give me the home page!
Browser
Server
Heres the home page plus a cookie.
Now, give me the news page (cookie is sent
automatically)
Ive seen you before Heres the news page.
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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!

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Magical Cookies

• The term cookie comes from an old programming
  hack, called Magical Cookies.
• If a programmer couldnt make two parts of a
  program communicate, she would create a magical
  cookie, a small text file containing data to
  transfer between program parts.

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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?

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Cookie Anatomy
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Cookie Anatomy

• Version 0 specifies six cookie parts
• Name
• Domain
• Path
• Expires
• Secure

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Managing Cookies
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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

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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

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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
• Lets take a look...

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IE Cookie Files

• Cookie files are stored within a cookies
  directory under windows C\windows\cookies
• Each cookie gets its own name.
• Lets take a look...

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Cookie Block Software

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

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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?ReportTyp
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