Any electronic circuit can describe very simple or very complex collections of electronic components. In fact, an electrical circuit can have one component in it or it can have thousands of components in it. The circuit is simply the path that the electrons follow through the various components, with the components manipulating the flow of electrons in various ways to achieve specific goals.
Electronic circuits don’t necessarily have to consist of something that human being could even see. Some chips contain integrated circuits, which means that an entire circuit with all of its attendant components is contained in a very small device. Some of these devices are literally no bigger than a fingernail but have enormous processing power and beyond. Microcontrollers are types of integrated circuits that actually constitute an entire computer shrunk down to a very small size and that can easily be integrated into other circuits, greatly expanding their functionalities and allowing for programming, which opens up a great many possibilities for automation, monitoring and so forth.