Spyware is a type of malicious software-or malware-installed on a computing device without the end user's knowledge. It can invade devices, steal sensitive information and Internet usage data, and forward it to advertisers, data companies, or external users.www.spyic.fr If any software is downloaded without the user’s authorization, it can be classified as spyware. Spyware is controversial because even if it is installed for relatively harmless reasons, it may infringe on the privacy of the end-user and may be abused.