Classical optics is dependent on the wave properties of light with key concepts based on the Huygens principle and Maxwell's equations. Basically, it deals with the continuous property of light. Modern optics started with the discovery that light is quantized which started with Einstein's photoelectric effect.

A laser is a device that emits coherent light and is characterized according to its wavelength in a vacuum. It is also the acronym for light amplification by stimulated emission of radiation. It was discussed that laser emits coherent light, this property is what sets lasers apart from any other sources of light. Coherence refers to the laser being able to emit a narrow beam of light making it a good light source for experiments such as diffraction. Lasers are not only applied in science and technology research but are widely applied in the field of communications, medicine, industry, military, law enforcement, commercial products, and entertainment.

In the realm of communication, we mean laser communication in space and the most recent is the fiber-optic communication through optical fibers to transmit telephone signals, internet communication, and cable television signals. In medicine, lasers are very useful in surgeries due to their very high precision outputs more particularly in eye surgeries where precision is of utmost importance. Industries use lasers in cutting very thin materials, welding and marking parts of the materials, 3D printing, etc. In military lasers are used as directed-energy weapons. In law enforcement lasers are used in fields such as LIDAR traffic enforcement and latent fingerprint detection in the forensic identification field. Commercial products use laser printers, barcode scanners, laser pointers, holograms, etc. In the world of entertainment, lasers are used in optical discs, laser lighting displays, laser turntables, etc.