Passive components in electronics are basic electronic components that do not require a power source to operate. They are fundamental building blocks in electronic circuits and perform various functions such as storing energy, filtering signals, controlling voltage and current, and providing impedance to the circuit. The main types of passive components include:

1. **Resistors**: Resistors are used to resist the flow of electric current in a circuit. They are commonly used to control the amount of current flowing in a particular part of the circuit or to provide specific voltage levels.

2. **Capacitors**: Capacitors store electrical energy in an electric field. They are used in circuits for energy storage, power conditioning, noise filtering, and signal coupling.

3. **Inductors**: Inductors store energy in a magnetic field when current flows through them. They are used in circuits to control the flow of current, filter signals, and store energy temporarily.

4. **Transformers**: Transformers consist of two or more coils of wire that are used to transfer electrical energy between circuits through electromagnetic induction. They are commonly used to step up or step down voltage levels in power supply circuits.

5. **Diodes**: Diodes allow current to flow in one direction while blocking it in the opposite direction. They are used in rectification, signal demodulation, voltage regulation, and protection circuits.

6. **Transducers**: Transducers convert one form of energy into another form. For example, piezoelectric transducers convert mechanical energy into electrical energy and vice versa.

7. **Switches**: Switches are used to control the flow of current in a circuit by making or breaking electrical connections. They are essential for controlling the operation of electronic devices.

These passive components are indispensable in electronic circuits and are used in various applications across industries ranging from consumer electronics to telecommunications to automotive systems.