A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is usually a small text file given an ID tag that is stored in your computer's browser directory or program data subfolders while the user is browsing that website. The browser sends the cookie back to the websites server to notify it of the user's previous activity every time the user visits.
Cookies were created to be a reliable method for websites to remember stateful information or to record a user's browsing activity when a user returns to a website for a second time. Cookies can be used for recording items in a shopping cart, contact form data, your bank card number, your login preferences and/or recording which pages were visited by the user as far back as months or years ago.
A cookie supplied from the website being visited is called first party cookies. Some websites will fetch additional pieces of information, such as a javascript file, from other locations and this second location may set a cookie on your computer, these are termed as third party cookies.
Cookies cannot carry viruses or install malware on a host computer although they can be used for tracking user activity, tracking cookies and especially third-party tracking cookies are commonly used as ways to compile long-term records of an individual’s browsing history. For some people this can be a privacy concern and the UK, EU and USA have introduced rules relating to the use of cookies.
Not all cookies are used for tracking a user's browser habits, some, such as authentication cookies, perform essential functions in the modern web. They are used by web servers to know whether a user is logged in or not, and which account they are logged in with. Without this the site would not know whether to send a page containing sensitive information, or require the user to authenticate themselves by logging in. The security of an authentication cookie generally depends on the security of the issuing website and the user's web browser but in most cases sensitive cookie data would be encrypted.
Top Cat! The most effectual Top Cat! Who's intellectual close friends get to call him T. C., providing it's with dignity. Top Cat! The indisputable leader of the gang. He's the boss, he's a pip, he's the championship. He's the most tip top, Top Cat.
Social Media
Facebook Social widgets are used on already more than 19% of all websites & blogs (source w3techs). When you visit a website with a Facebook Like button (or any other FB functionality) your browser will send data (and your IP address) to Facebook Recently it was made public that Facebook creates shadow profiles of logged out users This means that even if you are logged out or not a Facebook member, they still keep track of the websites and articles your IP address (and other browser unique identifiers) was looking at