1. Density waves of electrons, created when light hits the surface of a metal under precise circumstances.
2. Electromagnetic, or electronic waves, which occur inside and on the surface of metals and other materials.

Plasmons have the same frequencies and electromagnetic fields as light, but their sub-wavelength size means they take up less space.

Plasmon waves exist as optical frequencies. The higher the frequency of the wave, the more information which can be transported. Optical frequencies are about 100,000 times greater than the frequency of today's electronic microprocessors.

What makes plasmons of current interest is their ability to confine light to nanoscale regions which are much smaller than the wavelength of light.

Because these density waves are generated at optical frequencies, very small and rapid waves, they can theoretically encode a lot of information, more than that which is possible for conventional electronics.