Dental lasers are becoming an integral part of contemporary dentistry. Lasers can artistically sculpt soft tissues while providing precision, increased visibility, improved impression techniques; predictable healing with decreased scarring, reduced anesthesia and postoperative swelling. With the introduction of the hard-tissue laser, cosmetic bonding procedures are more predictable by providing enhanced bond strength, more comfortable by requiring little to no anesthesia, and less invasive via controlled removal of tooth structure. To protect the faith of patients on the clinician, we must be familiar with the fundamentals of laser physics and tissue interaction so that the proper laser device is used to obtain the treatment objective safely and effectively. This review will discuss about laser physics in detail to make its use more scientific and reliable for both clinicians and patients.