Malware is a combination of the terms malicious and software. It refers to a variety of hostile programs, such as a virus or a Trojan horse, designed to damage or disrupt a computer. It gathers information about a computer without the user’s permission or knowledge.
Adware is software that automatically downloads and display advertisements in the Web browser without user permission. When a user visits a site or downloads software, sometimes a hidden adware software is also downloaded to display advertisement automatically. This can be quite irritating to user. Some adware can also be spyware.
Spyware is software that gathers information about a user without his knowledge. Spyware can get into a computer when the user downloads software from the Internet. Spyware can search the contents of a hard disk, address book of an e-mail, or any information about the computer, and transmits the information to the advertisers or other interested parties.