An inductor is a component that can convert electrical energy into magnetic energy and store it. The structure of an inductor is similar to a transformer, but with only one winding. Inductors have a certain inductance, which only impedes changes in current. If an inductor is in a state where no current passes through, it will attempt to obstruct the current from flowing through it when the circuit is turned on; If an inductor is in a state where current is passing through, it will attempt to maintain a constant current when the circuit is disconnected. Inductors are also known as chokes, reactors, and dynamic reactors. Inductors are generally composed of a skeleton, winding, shielding cover, packaging material, magnetic core or iron core, etc.

Skeleton refers to a bracket used for winding coils. Some large fixed or adjustable inductors (such as oscillating coils, blocking coils, etc.) are mostly wrapped with enameled wire (or yarn wrapped wire) around the skeleton, and then the magnetic core or copper core, iron core, etc. are inserted into the inner cavity of the skeleton to increase their inductance. The skeleton is usually made of plastic, laminated wood, or ceramic, and can be made into different shapes according to actual needs. Small inductors (such as color coded inductors) generally do not use a skeleton, but directly wrap the enameled wire around the magnetic core. Hollow inductors (also known as derived coils or hollow coils, commonly used in high-frequency circuits) do not require magnetic cores, skeletons, or shielding covers. Instead, they are first wound on a mold and then removed from the mold, with a certain distance between the coils.

A winding refers to a set of coils with a specified function, which is the basic component of an inductor. There are single-layer and multi-layer windings. There are two forms of single-layer winding: dense winding (when the wire is wound one by one) and intermittent winding (when the wire is wound at a certain distance between each turn); There are various types of multi-layer windings, such as layered flat winding, random winding, and honeycomb winding.

Magnetic cores and magnetic rods are generally made of materials such as nickel zinc ferrite (NX series) or manganese zinc ferrite (MX series). They have various shapes such as "I" shape, column shape, cap shape, "E" shape, and can shape.

The main materials for iron core are silicon steel sheets, Permalloy, etc., and their shapes are mostly "E" - shaped.

To prevent the magnetic field generated by some inductors from affecting the normal operation of other circuits and components, a metal screen cover (such as the oscillation coil of a semiconductor radio) is added to the shielding cover. The use of shielded inductors will increase coil losses and lower Q values.

After winding some inductors (such as color coded inductors, color ring inductors, etc.), the coil and magnetic core are sealed with packaging materials. The packaging material is made of plastic or epoxy resin.