What does an idle CPU do?

In the last post I said the fundamental axiom of OS behavior is that at any given time, exactly one and only one task is active on a CPU. But if there’s absolutely nothing to do, then what? It turns

Normal CPU Temperature While Gaming and Idle - Don't Get Burned

database - Significantly downgrading a server processor in light of extremely idle CPU? - Server Fault

25 CPU Usage When Idle

Execute programs when your system enters and leaves idle state - gHacks Tech News

System Idle Process High CPU Usage [Solved] - Driver Easy

ENERGY STAR Ask the Experts, Products

3 Ways to Fix System Idle Process High CPU in Windows 11

Understanding I/O Wait (or why 0% Idle can be OK) - Your Embedded and IoT Software Partner

14: CPU idle time duration. Download Scientific Diagram

Why is the System Idle process using 80% of my CPU all the time?