How does spyware function once installed on a system?

Spyware operates primarily by gathering and transmitting sensitive data without the user's knowledge or consent. Once installed on a system, it can monitor user activity, capture keystrokes, track online behavior, and collect personal information such as passwords, credit card numbers, and browsing habits. This data is then often sent to remote servers controlled by cybercriminals, which can lead to identity theft, financial loss, or unauthorized access to personal accounts.

While some forms of malicious software may replace applications, display advertisements, or modify system settings, these functionalities are not the primary purpose of spyware. Its main goal is to covertly harvest sensitive information to exploit the user, which is what distinguishes it from other types of malware. Thus, the key aspect of spyware is its focus on data collection and subsequent transmission to malicious entities.