Circuit

A traced pathway of computations inside a neural network that produces one specific behavior, like the chain of steps that resolves "he" to the right person in a sentence.

When a model does something specific, like predicting that "Paris" follows "The capital of France is," a small subset of its neurons and connections are doing the heavy lifting. Researchers trace that subset and call it a circuit. Think of tracing which wires in a building's electrical system control one particular light: the building has thousands of wires, but only a handful matter for that light. Circuits can be simple (a few processing components working together) or sprawling and layered, depending on how complex the behavior is.

Builder example

Circuit analysis offers the most concrete form of AI explanation available: a traceable chain of computation you can verify, rather than the model's verbal self-report. As this research matures, it could power debugging tools that show exactly which internal pathway produced a hallucination or a refusal.

Common confusion: A circuit here is a traced computational pathway inside software, with no relation to physical electronic circuits. The word is a metaphor for how information flows through layers of a neural network.