Small parts help machines work. 
Tiny parts help machines work. 
Electronic components are the small parts in a machine. 
Some parts are called active components. These parts need a power source to work. A transistor is a common active component. It can switch signals or make them stronger. 



Electronic components are the tiny building blocks of modern machines. 
There are different ways these parts work. Some are called active components because they need a power source to operate. For example, a transistor can switch signals or make them stronger. 


History shows how these parts have changed our world. Transistors are often called the invention of the twentieth century. They changed electronic circuits forever by allowing for smaller and faster machines. Before modern transistors, people used vacuum tubes to control electricity. These older parts were much larger than the tiny components we use today. Now, many parts are integrated into single packages called integrated circuits. This allows a huge number of tiny parts to live inside one small chip.
Scientists and engineers use many specific types of components. One very common part is the MOSFET, which is a type of field-effect transistor. 

You can see these components in almost everything you touch. The screen on a phone might use LED technology to show pictures. 

An electronic component is a discrete physical entity used within an electronic system. These devices are designed to affect electrons or their associated fields. Most components are industrial products available in singular forms. They are distinct from electrical elements, which are conceptual abstractions used to represent idealized components. In a practical circuit, components connect via electrical terminals or leads. These leads often join other parts over wire to form a functional circuit. Such circuits can perform specific tasks like acting as an amplifier, a radio receiver, or an oscillator.
Engineers classify these components into three main categories: active, passive, or electromechanical. The classification depends on how the component handles energy. Active components rely on an external source of energy to operate. In circuit analysis, engineers often focus on the AC circuit, which is an abstraction that ignores DC power supplies. Under this view, an active component like an oscillator appears to produce energy, even though it actually consumes energy from a DC source. Active components can often inject power into a circuit. 
Passive components differ because they cannot introduce net energy into a circuit. They do not rely on a separate power source beyond what is available in the AC circuit. Because of this, they cannot amplify a signal. However, they can still increase voltage or current, such as a transformer does. Common two-terminal passive components include resistors, capacitors, and inductors. Resistors oppose current and pass it in proportion to voltage. Capacitors are used to store and release electrical charge. They are vital for filtering power lines or tuning resonant circuits. 
Electromechanical components represent a third category. These devices carry out electrical operations by using moving parts or electrical connections. Some passive components with more than two terminals follow the principle of reciprocity. This means they behave predictably in both directions. However, there are rare exceptions like the circulator, which is used at microwave or optical frequencies. In contrast, active components with more than two terminals generally lack this reciprocal property. 
Transistors are among the most significant components ever created. They are semiconductor devices used to amplify and switch electronic signals. The transistor is often called the invention of the twentieth century because it changed electronic circuits forever. One of the most common types is the MOSFET, or metal–oxide–semiconductor field-effect transistor. These are manufactured in massive quantities worldwide. Other variations include the Bipolar Junction Transistor (BJT) and the Junction Field-Effect Transistor (JFET). 
Diodes are another essential group of components. A diode is designed to conduct electricity easily in only one direction. Some diodes have very specific roles. For example, a Zener diode allows current to flow "backwards" once a specific set voltage is reached. Light-emitting diodes, or LEDs, are a type of diode that emits light. 
Modern technology often uses integrated circuits, or ICs. An integrated circuit can perform many functions, such as digital-to-analog conversion or logical operations. These can be MOS integrated circuits, hybrid integrated circuits, or even three-dimensional ICs. This allows many tiny components to be packaged together into a single unit. This integration is what allows complex devices like microprocessors to exist. These advanced components represent the peak of modern electronic engineering and miniaturization.
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