What is a Cookie ?

what is a cookie

what is a cookie ?

A "cookie" is a small piece of information stored in your browser by a website you have visited.

Why does any website stores information on your browser ?

Usually a web browser requests the data from the website. Then the website responds to the  browser request and transfers the information. If you are visiting a website frequently, then the browser needs to request some of the common information every time. To overcome this ,the concept of cookies is introduced where a website will assign a unique ID to each of it's  visitors (for the 1st time). So this will help the websites to store your settings and preferences. 

What  information is stored in a cookie ?

information stored in a cookie

Will a Cookie store any personal information of a visitor?

No, A website doesn't store any of your personal information using a cookie. But there are other ways of using a cookie to target a  particular visitor.
Say for example you have liked a page on Facebook and commented in it. Then Facebook can  show an Ad which is related to that page. There is a maximum probability of clicking that ad  if it is related to your interest.In this way a website may get some advantage with cookies.
But not always cookies will be used for advertising only. Google may use some cookies to improve search results by storing the user settings like language and advanced search settings etc.
Facebook uses cookies to make your account more secure.It will alert you if your account is being accessed from a location other than your regular computer.This is why you will be asked to name a device for the first time visit to Facebook.

How can I delete my cookies stored in my browser ?

deleting cookies in Firefox and Chrome browsers

You can always delete the cookies if you think that your privacy is important than any other issues.
But do remember that most of the websites tries to improve them using cookies. So it is better to keep them for better browsing experience.