What characteristic describes spyware?

Spyware is characterized primarily by its function to collect information about the user without their knowledge or consent. It operates by monitoring user activity, gathering personal data, and often transmitting that information back to the creator of the spyware or other third parties for various purposes, such as targeted advertising, identity theft, or other malicious intents. This capability to stealthily observe and gather detailed data about a person's habits or personal information is what defines spyware, making it distinct from other types of software such as antivirus programs, performance enhancers, or encryption tools, which serve different purposes relating to protection, speed, and security.