What is a cookie?
A cookie is a piece of information in the form of a very small text file that is placed on an internet user’s hard drive. It is generated by a web page server, which is basically the computer that operates a website. The information the cookie contains is set by the server and it can be used by that server whenever the user visits the site. A cookie can be thought of as an internet user’s identification card, which tells a website when the user has returned.
What does a cookie look like?
Below is the content of a typical cookie. This one is from the Hotmail service and has the filename firstname.lastname@example.org (.txt is the standard filename extension for text files):
HMP1 1 hotmail.msn.com/ 0 1715191808
32107852 1236821008 29449527 *
The codes will only make sense to Microsoft’s MSN Hotmail servers.
What is the purpose of cookies?
Cookies make the interaction between users and websites faster and easier. Without cookies, it would be very difficult for a website to remember the user’s preferences or registration details for a future visit.
Session, or transient cookies
Cookies that are stored in the computer’s memory only during a user’s browsing session and are automatically deleted from the user’s computer when the browser is closed. These cookies usually store a session ID that is not personally identifiable to users, allowing the user to move from page to page without having to login repeatedly.
Session cookies are never written on the hard drive and they do not collect any information from the user’s computer. Session cookies expire at the end of the user’s browser session and can also become no longer accessible after the session has been inactive for a specified length of time, usually 20 minutes.
Permanent, persistent, or stored cookies
Cookies that are stored on the user’s computer and are not deleted when the browser is closed. Permanent cookies can retain user preferences for a particular web site, allowing those preferences to be used in future browsing sessions.
Permanent cookies can be used to identify individual users, so they may be used by web sites to analyse users’ surfing behaviour within the web site. These cookies can also be used to provide information about numbers of visitors, the average time spent on a particular page and generally the performance of the website. They are usually configured to keep track of users for a prolonged period of time, in some cases many years into the future.
What can I do to avoid cookies?
The easiest way to avoid cookies being retained on your computer or mobile device, is to use your browser in “Incognito” mode. Most modern browsers make this function available.
When used in incognito mode, the browser does not store any cookies on the hard drive, but only in memory. When the browser is closed, all the cookies are deleted. You can see how this works by logging into your account while in incognito. Close the browser and go back to the website. You will find you have to login again.
If you still have concerns about what cookies do, please do your own research to put your mind at ease.