Just like spyware, there is another entity of bad program which is just as similar to spyware but not as potent as spyware, it is called Adware. Adware is nothing but a software which is written so as to when installed will install some advertising materials into your pc, like pop-ups or toolbars which will again start displaying ads without your wanting it. Although adwares are harmless but some adwares act also as a spyware and hence could be dangerous for your PC.
One of the famous adware example is Hotbar and Cursor Mania, which comes along a toolbar and cursors that you download from their site. It will send the details of your site you visit and will show ads every now and then as a pop-up or pop-under or through other means and hence could be very irritating and pesky. These two are just an example. There are actually numerous such adwares which are waiting to be installed into your PC without your knowing. You should be well protected from such security vulnerability.
The best freeware program to control Adware is Lavasoft’s Ad-Aware. This is a freeware which can be used for free and one of the best known free tool to control adware which has been around for quite a while. If you ignore adwares thinking that they are not as dangerous as other security threats then you are actually making a big mistake and hence you should be well protected from adwares