Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Similar to a Trojan horse, spyware is a general term which refers to software that performs certain actions, gathering and collecting personal information about an individual or organization without their knowledge. Also called a spybot, tracking software, or adware, spyware can enter a computer as a virus or installed along a new program, as well as by hiding in certain peer-to-peer files shared online. Learn more about spyware programs and their prevention in this book.