Answer Description

Spyware is a malicious program that tracks user activity on the infected system. This could include any type of activity or data. It includes (but is not limited to) things like user inputs, browser activity, file data and anything else that can be tracked and captured on the system.

Wikipedia

Spyware (a portmanteau for spying software) is software with malicious behaviour that aims to gather information about a person or organization and send it to another entity in a way that harms the user by violating their privacy, endangering their device's security, or other means. This behaviour may be present in malware and in legitimate software. Websites may engage in spyware behaviours like web tracking. Hardware devices may also be affected.Spyware is frequently associated with advertising and involves many of the same issues. Because these behaviors are so common, and can have non-harmful uses, providing a precise definition of spyware is a difficult task.