Spyware

• Spyware is a type of program that can be installed on your computer without your knowledge. Its function is to monitor your computer and send back data to the owner. It can find out your Internet browsing patterns, steal your passwords and take your banking information. Spyware is usually installed when you download and install a program from a non-secure website, through direct file-sharing connections, email attachments and instant messages.  To counter spyware, a spyware detection tool can be used. A spyware detector is a software program that is designed to search for and remove spyware programs on your computer. A few that you can consider include SpyBot Search and Destroy, Windows Defender from Microsoft and Spyware Detector from Max Secure. As of 2011 these programs range in price from free to $100.
  
  

Viruses

• A computer virus is a small software program that can copy or duplicate itself and infect a computer system. This software is designed to spread from one computer to another and can interrupt a computer's operating system. A virus can corrupt your files, leaving them unusable. It can even use your own email messages to spread itself to other computers. Computer viruses are usually hidden in software programs that are downloaded from the Internet. To protect against infection you will need an antivirus program. A few that you can consider are Norton, AVG, McAfee and Kaspersky. As of 2011 these range in price from $50 to $100, although most have free or trial versions. You will also need to update it at regular intervals to protect against the latest threats.
  
  

Registry

• A registry is a batch of files that contain all transactions on your computer, such as program installation, web browsing and which applications were utilized. A registry contains thousands of entries. As the entries are filled with information, the registry causes the computer's program to slow down. Computers running the Windows OS often cannot remove the entry registries of programs even if they are uninstalled. To clean the computer registries, a registry cleaner is needed. A few registry cleaning programs that you can consider using include Microsoft Windows Registry and the PC Registry Cleaner, which cost around $50 as of 2011.
  
  

System

• When your computer is being operated, it stores files on the hard drive. As the files accumulate, they slow down the performance of the computer. Even when programs are uninstalled they still leave fragmented files behind, which can hurt the transfer speeds between your hard drive and CPU. To remove useless files such as those in your Internet browser's cache, temporary files and broken registry entries, you need a system cleaning tool. Some of the cleaning programs that you can consider are Advanced System Care from IObit Freeware, and CCleaner. As of 2011, these programs range in price from free to $50.