Mac OS X 10.6: What are cookies?
A cookie is a small file that a website creates and places on your computer. Cookies are normally helpful and harmless.
Cookies can store information that identifies you, such as your name and email address. A website has access only to the information you provide. For example, a website can’t determine your email address unless you provide it. A website can’t gain access to other information on your computer.
Safari accepts cookies only from websites you open. This might help prevent certain advertisers from storing cookies on your computer. You can change your cookies preferences so that Safari accepts no cookies or accepts all cookies.
For more information about cookies, open Safari and choose Help > Safari Help.