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Speaker 1: Welcome to brain Stuff from how Stuff Works dot com

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Speaker 1: where smart Happens. Hi, I'm Marshall Brain with today's question,

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Speaker 1: what is an Internet cookie? Cookies have for some reason

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Speaker 1: gained a rather sinister image, but they're really simple and harmless.

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Speaker 1: A cookie is just information stored as text strings on

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Speaker 1: your machine by a web server. A web server sends

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Speaker 1: you a cookie, and the browser stores it on the

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Speaker 1: hard disk. The browser then returns the cookie to the

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Speaker 1: server the next time the page is referenced. The most

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Speaker 1: common use of a cookie is to store a user

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Speaker 1: I D. For example, a cookie might contain the following

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Speaker 1: string I D equals nine six three five. Amazon dot

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Speaker 1: com is one site that uses this technique. When you

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Speaker 1: order a book, you fill out a form with your

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Speaker 1: name address. Amazon assigns you an i D in its database,

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Speaker 1: stores your information with that i D on its server,

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Speaker 1: and sends the i D to your browser as a cookie.

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Speaker 1: Your browser stores the i D on your hard disk.

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Speaker 1: The next time you go to Amazon, the idea is

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Speaker 1: sent back to the server. The server looks you up

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Speaker 1: by your I D and customizes the web page that

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Speaker 1: sends back to you. In essence, it knows who you

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Speaker 1: are so it can say welcome back, Joe Smith. You

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Speaker 1: might be wondering, is there any more to cookies than that. No,

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Speaker 1: they are simply text strings stored on the hard disk.

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Speaker 1: They are little text files. You can open them up

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Speaker 1: and see the strings that are being saved. There's nothing magic,

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Speaker 1: there's nothing complicated about it. Our cookies harmful? No, They're

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Speaker 1: just short text strings, and they can often make browsing

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Speaker 1: better by allowing a server to recall any customized information

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Speaker 1: you've set our cookies comment. Yes, the typical machine has

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Speaker 1: hundreds of separate cookies on the hard disk. Can cookies

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Speaker 1: transmit computer viruses? No, they're just text strings. Can accompany

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Speaker 1: read your personal information from your hard disc with a cookie? No?

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Speaker 1: Only the cookie that is sent in the first place

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Speaker 1: is returned to the server. It's not modified or manipulated

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Speaker 1: in any way. Be sure to check out our new

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Speaker 1: video podcast, Stuff from the Future. Join How Stuff Work

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Speaker 1: staff as we explore the most promising and perplexing possibilities

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Speaker 1: of tomorrow. The How Stuff Works iPhone app has arrived.

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Speaker 1: Download it today on iTunes.