An electronic circuit is a closed path or paths formed by the interconnection of electronic components through which an electric current can flow.
Physically, an electronic circuit can be as small as a pin point or cover many miles. They are constructed by connecting electronic components together with conductors, which allow electricity to flow between the components. Integrated circuits are small circuits constructed from a piece of semiconductor housed in a protective package. While larger circuits may be built by assembling electronic components onto a printed circuit board (PCB), which is used to mechanically support and electrically connect the components. Integrated circuits are typically used as components in larger circuits built onto PCBs. When components are connected using wire as the conductor, the circuit may be extended to cover or connect a large area.
Breadboards, perfboards or stripboards are common for testing new designs. They allow the designer to make quick changes to the circuit during development.
Electronic circuits can display highly complex behaviors, even though they are governed by the same laws of physics as simpler circuits.
An electronic circuit can usually be categorized as an analog circuit, a digital circuit, or a mixed-signal circuit (a combination of analog circuits and digital circuits).