Final answer:
User Account Control (UAC) is a technology used with Windows Vista, 7, 8/8.1, and 10 to enhance system security by directing and preventing unauthorized changes to the system.
Step-by-step explanation:
The technology used with Windows Vista, 7, 8/8.1, and 10 to enhance system security by directing and preventing unauthorized changes to the system is called User Account Control (UAC).
UAC is a feature that prompts users for permission or administrator credentials before allowing certain system changes or installations. It helps protect the system from malware and unauthorized modifications.
For example, if a user tries to install a program or make changes to system settings, UAC will pop up a prompt asking for permission or administrative credentials to proceed.