Post-silicon validation
Beginner
Running real programs on the real chip to find design mistakes that earlier tests on a computer missed.
Novice
Running manufactured chips under real conditions to find mistakes in the design itself that testing in simulation missed. Manufacturing test is different: it looks for physical flaws in each individual copy.
Expert
Four steps: detect, localize, find the root cause, fix. Silicon runs orders of magnitude faster than simulation, but engineers can see only a few internal signals, so localizing the bug takes most of the effort and depends on debug hardware built in at design time: trace buffers, triggers, scan dumps and clock control.