Short answers, pulled from the story.
An inductor is a passive two-terminal electrical component that stores energy in a magnetic field when an electric current flows through it. It is also called a coil, a choke, or a reactor, and it typically consists of an insulated wire wound into a coil. Along with capacitors and resistors, it is one of the three passive linear circuit elements that make up electronic circuits.
When the current through an inductor changes, the time-varying magnetic field induces a voltage in the conductor according to Faraday's law of induction. By Lenz's law, that induced voltage opposes the change in current that created it, so inductors resist any change in the current passing through them.
The unit of inductance in the International System of Units is the henry, with the symbol H. It is named for the 19th century American scientist Joseph Henry. Inductors typically have values ranging from 1 microhenry, or 10 to the minus 6 henries, up to about 20 henries.
The term inductor seems to come from Heinrich Daniel Ruhmkorff, who called the induction coil he invented in 1851 an inductorium.
The Q factor, or quality factor, of an inductor is the ratio of its inductive reactance to its resistance at a given frequency, and it is a measure of efficiency. The higher the Q factor, the closer the inductor comes to ideal behavior, and a well designed air core inductor may reach a Q of several hundred.
Inductors create and suffer from electromagnetic interference, and their physical size prevents them from being integrated onto semiconductor chips, so their use is declining in compact portable devices. Real inductors are increasingly replaced by active circuits such as the gyrator, which can synthesize inductance using capacitors and active components.