Website's have used cookies since the early days of the Internet. Meaning computer cookies are nothing new, just now more appearent. A website publisher must now state which data collectors they have and how the information is used.
For instance Google AdSense is a very popular advertiser used by millions of websites around the world. Hence Google is taking these requirements very seriously indeed.
Opting out of cookie usage can severely inhibit a website's functionality. You may not be able to communicate with the webmaster, fill in any forms or use certain pages.