They are simple ’text files’ which you can read using the Notebook program on your own PC. Typically, they contain two pieces of information: a site name and unique user ID.
The site then ’knows’ that you have been there before, and in some cases, tailors what pops up on screen to take account of that fact. For instance, it can be helpful to vary content according to whether this is your first ever visit to a site – or your 71st.
Some cookies are more sophisticated. They might record how long you spend on each page on a site, what links you click, even your preferences for page layouts and colour schemes. They can also be used to store data on what is in your ‘shopping cart’, adding items as you click.
The possibilities are endless, and generally the role of cookies is beneficial, making your interaction with frequently-visited sites smoother - for no extra effort on your part. Without cookies, online shopping would be much harder.
So why the paranoia? The answer probably depends on how you feel about organisations – both big business and government – storing information about you. There is nothing especially secret or exceptional about the information gathered by cookies, but you may just dislike the idea of your name being added to marketing lists, or your information being used to target you for special offers. That is your right, just as others are entitled to go along with the process.
When cookies first started to appear, there was controversy. Some people regarded them as inherently sneaky - your PC was being used (without warning) to store personal information about you, which could then be used to build a picture of your browsing habits.
In the UK, the Information Commissioner's Office (ICO) will be closely monitoring sites to make sure that they comply with this new legislation, so there will be no avoiding the regulations. Websites have had over a year to make the changes to their code, so there should be no excuses!
You can of course still change how cookies are stored on your machine by clicking on the 'Tools' menu or preferences in your internet browser.