The differences between a cookie and spyware can seem subtle at first, but there are many differences to how they operate and how they are ultimately used. There are security and privacy concerns for both.
Spyware is software that enters your computer without your knowledge. It will typically take private information on your computer and send it to a specific target. They can then use this information to steal credit card data and get your passwords. Unlike a virus, there is no set pattern to how spyware works, which makes it particularly dangerous. Spyware will send your personal data back to its target so long as you are connected to the Internet.
Cookies, on the other hand, are server-specific. This means that typically you have to be on a particular site for the cookies to be read. Cookies can be useful. For example, if you have a site that you login to regularly, that site might ask you if you want it to remember who you are. If you say "yes," it puts a cookie on your computer. The next time you come back it will "see" that cookie, match it with your user name and password and let you in. Additionally, cookies can help sites check to see whether you are a first-time visitor or you have been to the site before, thereby helping with statistical analysis of the amount of traffic coming to the site.
The Dark Side of Cookies
How to Remove Spyware
In the case of spyware, many tools are available to remove it from your system. Sunbelt Software's CounterSpy scans your computer, looks for spyware and will remove it whenever it locates it on your computer. It also has continuous protection, much like an antivirus program. CounterSpy is $19.95 after a 15-day free trial. A free alternative is Spybot Search and Destroy. This program doesn't have all of the extras that CounterSpy has, but it will do the job of locating and stopping any spyware on your system. Both CounterSpy and Spybot will also remove any cookies that they feel shouldn't be on your system.
A tool that is based around cookie removal is called CCleaner. This is a free program that will remove all tracking cookies from your computer regardless of what Web browser you use. It also has other added features such as a clutter-removal program that removes unused files from your system.