Sams Teach Yourself PHP in 24 Hours, Third Edition

Q&A

Q1:	Are any serious security or privacy issues raised by cookies?
A1:	A server can access only a cookie set from its own domain. Although a cookie can be stored on the user’s hard drive, there is no other access to the user’s file system. You can, however, set a cookie in response to a request for an image. So, if many sites include images served from a third-party ad server or counter script, the third party might be able to track a user across multiple domains.
Q2:	The query string looks ugly in the browser window. Would it be true to say that cookies are the neatest way of saving state?
A2:	Unfortunately, it isn’t that simple. At best, cookies are a transparent way of saving state. Some users, however, set their browsers to warn them ...