Simple definition
Simultaneous multithreading lets a physical CPU core execute instructions from multiple hardware threads.
Purpose and use
SMT, Simultaneous Multithreading, lets one physical core expose several logical execution contexts.
How does it work?
Those contexts can use selected shared core resources when workloads permit.
Example and verification
Measure throughput, latency and isolation effects with the actual applications.
Points to watch
Each context does not receive a complete independent core. Benefits and constraints vary by processor and workload.
In short
SMT can improve core utilization without multiplying identical physical resources.