Passive electronic components are ones that do not require a source of energy to perform their intended functions. Wikipedia describes them as “components incapable of controlling current by means of another electrical signal are called passive devices.”

So, basically, passive electronic components operate from the electricity or energy already in the circuit it is on, as they cannot generate energy, and they are not sources of energy. A passive electronic component does not generate power, but instead dissipates, stores, and/or releases it.  Every electronic circuit is an arrangement of electrical components designed to perform specific functions - passive components can become an active part of a circuit in unexpected ways. Transformers, categorized as passive, can raise voltage, but since they do not raise or lower power or energy they are classified as a passive element. Similarly, capacitors limit the interaction of electricity as just storing it, not supplying it.

There are two basic types of passive electronic components:

1. Dissipative or Lossy - these are predominantly resistors - components that does not have the ability to absorb any power from an external source.

2. Lossless - these components have no output or input of power flow and include capacitors, transformers and inductors. But all passive components dissipate some power due to minor internal resistances - so are not 100% lossless.

The table below shows the main differences between passive and active electronic components.

To summarize, the major types of passive components each have their unique element that stamps them passive. Resistors, like the name states, resist current flow; capacitors store energy; inductors resist changes in energy flow; while transformers can influence voltage by increasing or decreasing it to meet the needs of the electronic device. So while passive, they can have action without being classified active.