As you move from one page to the next in the store, the computer needs a reliable way of keeping track of what you have purchased. Web pages do not store that kind of information.
Shopping sites use cookies to help implement that function.
A cookie is a very small text file that is stored on your hard drive. Its main function is to keep track of what you have purchased so that the transaction can be carried out successfully. Cookies cannot search for and retrieve information from your hard drive nor can they be read by another server. SSL is the best method currently available to secure your transaction. Secure sites perform encryption through the use of a key that has two parts, a public key and a private key.