What type of malware gathers personal information about a user without their permission or knowledge?

Spyware is a type of malware specifically designed to collect personal information from users without their consent, often operating in the background and remaining undetected. It can capture data such as browsing habits, passwords, credit card information, and other sensitive data, which is then typically sent to third parties who may misuse this information.

This type of malware is insidious because it often disguises itself as legitimate software or affects the system in ways that are not immediately recognizable to the user. Users might unknowingly install spyware alongside other software, making it particularly challenging to detect and remove.

Adware, while also a form of software that can collect data, primarily focuses on delivering advertisements and is usually not as invasive as spyware. Trojans are deceptive programs that masquerade as legitimate applications but typically do not focus on gathering personal information unless they have spyware functionality. Worms are self-replicating malware that spread across networks but do not specifically gather personal information.