Cookie - types

There are three types of cookies: temporary, persistant and flash cookies.

Temporary cookies (Also ‘session’ or ‘transient’ cookies)

• Temporary:These are used to store only temporary information; deleted when the browser is closed at the end of a browsing session • Stored in memory Not written to the hard drive but stored in the temporary memory of a computer • Unique Create a unique session ID which does not personally identify users • Anonymous Used to anonymously identify users as they move from page to page within a site so that any information entered is remembered (e.g. items in a shopping basket)

Persistent cookies (Also ‘stored’ or ‘saved’ cookies)• Last longer Remain on the hard drive until they are erased or expire. In general they are set to last for a prolonged period which could be for weeks, months or years.

• Often make browsing easier Enhance or streamline the user experience by storing preferences or user data; websites use them to store information such as the sign-in name so people don’t have to sign-in again when returning to a website. • Provide customer insight Help websites track and analyse users’ online behaviour.

Example: How are persistent cookies used?A website may offer its contents in different languages. On the first visit, a user may choose to have the content delivered in French and the site may record that preference in a persistent cookie set in their browser. When they revisit that site it will use the cookie to ensure that the content is still delivered in French.

Flash cookies (Also ‘Local Shared Objects’ or ‘LSOs’)These are software files created on the ‘flash’ platform. They were devised to get around the cookie deletion challenge because they are not stored in the same way on a computer, and have the instruction and ability to recreate cookies after deletion.

• Similar functionality Work in the same way as regular HTTP cookies. • Not limited by size in the same way Can contain up to 100kb of data, versus the 4kb that an HTTP cookie can store. • Backup and restore of HTTP cookies Flash cookies can backup and reinstall deleted regular HTTP cookies. • Do not expire Flash cookies have no default expiration date. • Harder to delete Flash stores LSOs in different locations from HTTP cookies, so users may not know where to look to eliminate them and cannot use their web browsers to delete them. • Not flagged by security tools Most anti-spyware, antivirus, and anti-adware packages do not search for flash cookies. • Identify users Are not deleted using browser controls. Websites can use this to recognise returning visitors who have cleared their HTTP cookies.