电感器（inductor）是一种电路组件，会因为通过的电流的改变而产生电动势，从而抵抗电流的改变。这属性称为电感。

电感组件有许多种形式，依据外观与功用的不同，而会有不同的称呼。以漆包线绕制多圈状，常作为电磁铁使用和在变压器等中使用的电感也依外观称为线圈（coil）。用以对高频提供较大电阻，通过直流或低频的，依功用常称为扼流圈（choke），又称抗流圈。常配合铁磁性材料，安装在变压器、电动机和发电机中使用的较大电感，也称绕组（Winding）。导线穿越磁性物质，而无线圈状，常充当高频滤波作用的小电感，依外观常称为磁珠（Bead）。

An inductor, also called a coil or reactor, is a passive two-terminal electrical component which resists changes in electric current passing through it. It consists of a conductor such as a wire, usually wound into a coil. Energy is stored in a magnetic field in the coil as long as current flows. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, according to Faraday’s law of electromagnetic induction. According to Lenz's law the direction of induced electromotive force (or "e.m.f.") is always such that it opposes the change in current that created it. As a result, inductors always oppose a change in current, in the same way that a flywheel opposes a change in rotational velocity. Care should be taken not to confuse this with the resistance provided by a resistor.