Amber is the common name for fossil resin or tree sap that is appreciated for its inherent and interesting mixture of colours and it is widely used for the manufacture of ornamental objects. Although not mineralized, it is sometimes considered and used as a gemstone. Most of the world's amber is in the range of 30–90 million years old. Semi-fossilized resin or sub-fossil amber is called copal.

The Greek name for amber was ??e?t??? (Electron) and was connected to the Sun God, one of whose titles was Elector or the Awakener.

The modern term electron was coined in 1894, using the Greek word for amber (and which was then translated as Electrum) because of its electrostatic properties and whilst analyzing elementary charge for the first time. The ending -on, common for all subatomic particles, was used in analogy to the word ion.

Heating amber will soften it and eventually it will burn, which is why in Germanic languages the word for amber is a literal translation of Burn-Stone (In German it is Bernstein, in Dutch it is Barnsteen etc.). Heated below 200°C, amber suffers decomposition, yielding an "oil of amber", and leaving a black residue which is known as "amber colophony", or "amber pitch"; when dissolved in oil of turpentine or in linseed oil this forms "amber varnish" or "amber lac". As mentioned above, amber was well known for its electrostatic properties since antiquity (though not identified as such until the concept of electronic charge became clear).