The Tesla turbine, patented by Nikola Tesla in 1913, is a non-conventional bladeless turbine which works on the principle of boundary layer. It consists of a number of parallel discs fixed on a shaft with gaps between the discs. The fluid is made to flow tangential to the discs inside a casing. Momentum is transferred from the fluid to the discs due to viscous and adhesive forces. Not much work has been carried out in the first half of twentieth century but decent amount of published research and study has been done in the latter half. Some papers suggests modifications while some provide explanations for different performances and efficiencies at various parameters. This paper intends to review the principle, working, design modifications and the factors affecting the performance of Tesla turbine.