“Web cookies are small bits of saved data that websites can store in your browser,” John Gruber writes for Daring Fireball. “Cookies are restricted by domain; if example.com stores a cookie in your browser, the only website your browser sends that cookie back to is example.com.”

“But, by default, most desktop web browsers allow ‘third-party’ cookies,” Gruber explains. “That means if a page on example.com loads JavaScript from a different domain, that JavaScript is able to use cookies too. One common use is by ad networks; an ad network can set a cookie and then access that same cookie from any website that uses the same ad network.”

Gruber writes, “Google makes use of such cookies to display its ads. Ad networks that use cookies in this manner do so in order to track users across websites.”

All major browsers give the user control over cookie permissions. Usually, with three options:

• Accept cookies from anywhere (i.e., allow third-party cookies)
• Accept cookies only from visited websites (disallow third-party cookies)
• Don’t accept any cookies at all

Gruber explains, “The difference with Safari is in the default for this setting. Most major browsers default to the first option, allowing all cookies. Safari and Mobile Safari default to the second, allowing only first-party cookies.”

Much more in the full article – recommended – here.

[Thanks to MacDailyNews Reader “Fred Mertz” for the heads up.]

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Google’s tracking of Safari users could prompt FTC investigation – February 18, 2012
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