Spyware is a type of malware that is different from computer virus. It does not replicate itself. It does not even infect a computer when there is a connection between an infected computer and a clean computer. In most cases spywares are delivered through sharewares and freeware and free peer to peer file transfers. The spywares remain hidden in these types of apparently innocent software and installed to the system when the host program is installed. Moreover, as these spywares are different in nature from the usual computer viruses they are not even detected by the regular anti virus software that we have. So, the user absolutely is not aware of the existence of the spyware in the computer. You need a spyware scanner to detect and delete spyware.
Spyware is basically a malware that is aimed at spying your internet behaviour. It keeps track of the websites you visit and other things that will tell its authors about your online interests. The information is send to the people who initiate the spywares and they analyze the data to configure your internet usage and the trigger advertisements that are most likely to grab your attention. Though these practices are not harmful to your system, they are unethical as they are breaching your privacy. Moreover, the spywares use your computer resources and internet bandwidth to collect, store and send information. Therefore it is very much important that you delete spyware and ensure your online privacy.
Apart from these not so harmful collections of user statistics, spywares are used for far more deadly actions. There are spywares that can even steal confidential information from your computer like your bank account numbers, credit card numbers and passwords to these accounts. They do these by logging the keystrokes when you enter the information at the online forms. So, you are not really protected even when you are using a secured server to make your online transactions. Only if you delete spyware from your PC with a spyware cleaner, you can ensure your privacy and security.
To stay protected from various threats of spywares, you need to first detect them and then remove then successfully from the system. For the most effective way of spyware removal is to scan the PC regularly with anti spyware software. They scan your computer for traces of spywares and delete spyware from the hard disc that ensures complete protection.