LYCOS RETRIEVER 
Cookie: Users
built 158 days ago
The expiration date tells the browser when to delete the cookie. If no expiration date is provided, the cookie is deleted at the end of the user session, that is, when the user quits the browser. As a result, specifying an expiration date is a means for making cookies to survive across browser sessions. For this reason, cookies that have an expiration date are called persistent.
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There are occasions on which you may wish to delete a cookie from a user's computer. This could be if, for example, you want to log the user out of a system (perhaps they are on a public computer). Deleting a cookie is quite simple to do because all you have to do is to set the expiry time in the past. By doing this, the cookie will be automatically deleted as soon as it is created, and will remove any data that already exists there. The simplest way is using:
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[One] possibility is that you may be running software that interferes with cookie usage. There are many filtering and blocking software packages available for Internet users these days, and many of them ... filter cookies. If you are running software like this, then your computer may not receive or send cookies. This will cause sites you visit to assume you are not accepting cookies.
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This code takes the current time (using time()) and then adds 3600 seconds to it, and uses this value to set as the expiry time for the cookie. Basically this means that the cookie will remain on the user's computer for an hour (it expires 3600 seconds (1 hour) from the current time). For one week (for example) you would set the cookie as:
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If, for example, a cookie contains the total value a user has to pay for the items in their shopping basket, changing this value exposes the server to the risk of making the attacker pay less than the supposed price. The process of tampering with the value of cookies is called cookie poisoning, and is sometimes used after cookie theft to make an attack persistent.
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The name cookie derives from UNIX objects called magic cookies. These are tokens that are attached to a user or program and change depending on the areas entered by the user or program.
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