Spyware: This is a computer software so get installed without you know anything about. It is a threat to your Privacy. This will monitor your computer and it will save data about what you are doing on your computer. etc. What websites you visiting.. This may also follow software so you download. What can Spyware do? - Slow down system Performance. - Can crash the computer. - Give weird CPU usage. - Change your homepage. Adware: This is follow programs you download from the internet. The work to adware is basically to advertising the user to buy a program for etc. This may give pop up.This can also look what Internet sites you visit. It can also download spyware without you knowing about it. Adware is often in Sharewares. Sharware means trial versions. Here is an etc of a Adware program "Yahoo Messenger". What can Adware do? - Give pop up windows with advertising. - Can see what sites you visit. - May Download Spyware There are several tools out their today so can protect you against it. Downloads: http://www.safer-networking.org/en/download/index.html (Spybot Search and Destroy) http://www.javacoolsoftware.com/spywareblaster.html (SpywareBlaster) http://www.lavasoft.com/ (Ad-Aware)