Spyware is a subset of malware, or malicious software, intentionally deployed against users and downloaded onto their devices. Once installed, spyware logs information from the user’s device and web browsing habits and relays it to an outside party where the information is leveraged for fraud.
Spyware may also take the form of nuisance or unwanted software that collects information on browsing habits, relaying it to a third party for commercial purposes.
Among the more nefarious uses of spyware is collection of credentials or bankcard information. Some spyware downloads additional bothersome or dangerous software after the initial download. Still others alter the device settings affecting security, privacy, and performance.
Intrusion detection systems for enterprise networks and device layer protections for users are ways to prevent the installation of mischievous or risky programs. The best prevention, however, is to view all external email attachments and advertising banners as an access point through which spyware can infect one’s device.
"I was wondering why my life seems to be impeccably synced with relevant advertising. That is, until I discovered that there's a ton of spyware on my device needing to be uninstalled. I suppose I should be thankful that it wasn't a keylogger."