Today's World is of Computer

from wikipedia :- An  cookie  (also called  web cookie ,  Internet cookie ,  browser cookie  or simply  cookie ) is a small piece of data sent from a website and stored in the user's  web browser  while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember  stateful  information (such as items added in the shopping cart in an online store) or to record the user's browsing activity (including clicking particular buttons,  logging in , or recording which pages were visited in the past). They can also be used to remember arbitrary pieces of information that the user previously entered into form fields such as names, addresses, passwords, and credit card numbers. Other kinds of cookies perform essential functions in the modern web. Perhaps most importantly,  authentication cookies  are the most common method used by web servers to know whether the user is logged in or not, and which account they are logged in with. Without such a mechan