When your computer starts slowing down, it can indicate the presence of spyware that is quietly working in the background. Although most spyware programs are not generally destructive in nature, there are a lot that can harm your computer in the long run. Spyware tracks your surfing patterns and accesses other sensitive information stored in your computer, and sends them to some other computers on the net. Spyware are designed to search through your hard drive and send information to its creator, such as the software you have installed, your e-mail list, the Web sites you visit, login passwords, and credit card numbers. Cyber criminals can misuse these vital pieces of private information, which is why it is important to remove spyware from computers.