Definition Wednesday: What are cookies?

Cookie with a "no" sign inside

Cookies are small files which are stored on a user's computer. They are designed to hold a modest amount of data specific to a particular client and website, and can be accessed either by the web server or the client computer. This allows the server to deliver a page tailored to a particular user, or the page itself can contain some script which is aware of the data in the cookie and so is able to carry information from one visit to the website to the next. Cookies may be used by frequently visited website so a user does not need to sign in every time. A cookie can also track one's preferences to show them websites that might interest them.

What's in a cookie?

Each cookie is effectively a small lookup table containing pairs of (key, data) values - for example (firstname, John) (lastname, Smith). Once the cookie has been read by the code on the server or client computer, the data can be retrieved and used to customize the web page appropriately.

Are cookies secure?

There is a lot of concern about privacy and security on the internet. Cookies do not in themselves present a threat to privacy, since they can only be used to store information that the user has volunteered or that the web server already has. Whilst it is possible that this information could be made available to specific third party websites, this is no worse than storing it in a central database. If you are concerned that the information you provide to a web server will not be treated as confidential then you should question whether you actually need to provide that information at all.

Should I delete my cookies?

Tech Support asks the Cookie Monster to delete his cookies.  He says no.

Cookies are very useful to navigate the Internet, but some, out an abundance of concern about privacy, choose to delete cookies. Many tech support outlets will request you delete the cookies if you are experiencing internet browser trouble or have a spyware/malware infection on your computing device.

The original developers of cookies intended that only the website that originally distributed cookies to users could retrieve them, therefore returning only data already possessed by the website. However, in practice programmers can circumvent this restriction. Possible consequences include the placing of a personally-identifiable tag in a browser to facilitate web profiling or the use of cross-site scripting to steal information from a user's cookies.

If you would like to delete your cookies, instructions may be found at:

Source 1 | Source 2

Last Updated: August 23, 2016