Double Opt-In - A user has subscribed for a newsletter or other email marketing messages by explicitly requesting it and confirming the email address to be her own. This is usually done by responding to a confirmation email sent to the email address in question.
This eliminates the chance of abuse where somebody submits somebody else's email address without their knowledge and against their will.
Cookies - Cookies are small files stored on the visitor's computer which record information that is of interest to the merchant site. Despite concerns that some people have, cookies are in no way dangerous -- and can not be used to steal names, email addresses, phone or credit card numbers. With affiliate programs, cookies have two primary functions: to keep track of what a customer purchases, and to track which affiliate was responsible for generating the sale (and is due a commission).
