What are cookies and how do they work?

A cookie is a text file containing information that can be remembered by a web browser between pages. When an individual uses a web browser to access the internet their browser can create cookies which are stored on the user's computer. Cookies are not programs and therefore cannot contain viruses or other malicious software. They are purely a string of text and numbers.

Session cookies only last during a single visit. When you close your web browser the session cookie information is automatically removed from your computer.

Persistent cookies are stored by the user's web browser even when the web browser has been closed, so that the next time a user goes back to the website that originally set the cookie, the web site can read information back from the cookie. Persistent cookies have an expiry date which controls when they are automatically deleted. This can be anything from a few minutes to several years, depending on your own browser settings.