Your analogy to an online store breaks down as well ... you have a users IP address, and what part they accessed, thus you have logged this user. What supermar

Your analogy to an online store breaks down as well ... you have a users IP address, and what part they accessed, thus you have logged this user. What supermarkets don't do and what cookies do allow now is for you to track said user over multiple visits. If I go to a supermarket and buy food and pay with cash, they don't have a record of me having come in three days ago to purchase the exact same items. With a cookie that is set for 12 years in the future you will know it is me visiting again, and again, and again.