Since 1994, cookies have been used on Internet websites to (among other things) track the behavior of users. Web suffers who worried about privacy gradually found ways to get around cookies, or deleted them on a regular basis. Most people felt better.

Then came the Flash cookie.

Most Internet users are blissfully unaware of Flash cookies (also known as local shared objects. But half or more of all Internet sites now use them - for pretty much the same purposes that traditional cookies were used. The problem is that most web surfers don't know they're even there - much less how to get rid of them. They keep on deleting their traditional cookies and they feel safe and protected. In some cases the flash cookie (the one you don't knwo about) even restores the traditional cookie to your Internet browser's cache.

There have been a number of recent articles on Flash cookies. Examples include Wired and Lifehacker. The easiest tool to use to see and delete Flash cookies is here, at Macromedia.com.