What does a capacitor do?

The function of a capacitor is primarily to store electric charge, which directly relates to the concept of storing potential energy. When a capacitor is connected to a voltage source, it accumulates charge on its plates, creating an electric field between them. This stored charge represents potential energy, as it can be released back into the circuit when needed. The ability of a capacitor to hold this charge until it is discharged is essential in various applications, such as smoothing out voltage fluctuations in power supplies or timing applications in electronic circuits.

The other functions mentioned, like insulating wires or creating electric fields, are not the primary roles of a capacitor. While capacitors do create an electric field across their plates when charged, the better description of what a capacitor fundamentally does relates to its ability to store potential energy.