Welcome to brain Stuff from how Stuff Works dot com where smart Happens. Hi, I'm Marshall Brain with today's question, what is an Internet cookie? Cookies have for some reason gained a rather sinister image, but they're really simple and harmless. A cookie is just information stored as text strings on your machine by a web server. A web server sends you a cookie, and the browser stores it on the hard disk. The browser then returns the cookie to the
server the next time the page is referenced. The most common use of a cookie is to store a user I D. For example, a cookie might contain the following string I D equals nine six three five. Amazon dot com is one site that uses this technique. When you order a book, you fill out a form with your name address. Amazon assigns you an i D in its database, stores your information with that i D on its server, and sends the i D to your browser as a cookie. Your browser stores the i D on your hard disk.
The next time you go to Amazon, the idea is sent back to the server. The server looks you up by your I D and customizes the web page that sends back to you. In essence, it knows who you are so it can say welcome back, Joe Smith. You might be wondering, is there any more to cookies than that. No, they are simply text strings stored on the hard disk. They are little text files. You can open them up and see the strings that are being saved. There's nothing magic,
there's nothing complicated about it. Our cookies harmful? No, They're just short text strings, and they can often make browsing better by allowing a server to recall any customized information you've set our cookies comment. Yes, the typical machine has hundreds of separate cookies on the hard disk. Can cookies transmit computer viruses? No, they're just text strings. Can accompany read your personal information from your hard disc with a cookie? No?
Only the cookie that is sent in the first place is returned to the server. It's not modified or manipulated in any way. Be sure to check out our new video podcast, Stuff from the Future. Join How Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The How Stuff Works iPhone app has arrived. Download it today on iTunes.