Spyware 

Nowadays there are plenty of parasites. All of them have different definitions, but grassroots sometimes improperly use those definitions. Such programs as adware or Parasiteware aren’t the same as spyware.
Spyware is less dangerous than some Parasiteware and malware, but creates bigger threat than adware. Illegally used spyware can record keystrokes (so called keyloggins); it tracks user’s activity online and offline, logs passwords, personal data and confidential information. Obtained data is used by third parties. Also there is a legal spyware software. It is used for computer users’ monitoring and supervision, for remote administration and protection of confidential information. It can be very successfully used as Internet monitoring tool.
Spyware used for illegal purposes can create great danger for user’s privacy. Spyware comes to computer from certain web sites, bundled with freeware or other downloaded files. It is installed into computer system without user’s knowledge or permission. Most spyware works in invisible mode and collects any available information that must be sent to third parties.

• Spyware is able to obtain:
• Credit card numbers
• E-mail content
• E-mail addresses
• URL addresses
• Screenshots
• Every word that was written in ICQ/MSN/AIM/AOL/Yahoo!
• Logs form IRC chats.
• Passwords
• Name, surname, home and work address
• Names and addresses of a friend, relatives, co-workers, etc.
• Sites that you’ve been visiting.
• Texts that you’ve been typing.
• Even view taken to webcam.

This means that every step you do on your PC is spied, logged and sent to somebody. Obtained data is used for third parties profit. E-mail addresses are used for spam. Your online habits are used for advertising purposes. Your personally identifiable information can be used for carding or identity theft.
Spyware can be prevented. Firstly it’s essential to have anti-spyware with a real-time protection feature. It’s better to get not free anti-spyware, because good quality costs. Free anti-spyware are good but still not as better as purchased programs. The best recommended free anti-spyware SpyBot and best software you are able to purchase is Spyware Eliminator.
Be sure that your Windows Messenger service is disabled. Never give up personal facts during IRC chats or talking on instant messenger.
Always check your system for unnecessary programs or components. When your PC slows down or unknown programs are running in system tray it’s a signal that you may have spyware. You also can find unwanted shortcuts on desktop of unknown programs. It’s very important to remove them.
Get yourself a decent firewall like Zone Alarm or Sygate. They are perfect for Windows. It improves security and protection from spyware, adware, malware, crackers, hackers and lammers and many more intruders.
And the last, but not less important tip- always read End of User License Agreement before installing anything. You have the right to know what are you installing and sometimes EULA warns about parasite bundled with freeware. Be careful.