In current time, reversible logic gates are being used very fast due to its ability to design the more complex circuit with less power dissipation. Power consumption is the main factor in low-power VLSI design. Reversible logic gates reduce power in the big amount by eliminating the power loss during a loss of one bit of data in simple operations during conventional logic gates. The main purpose of this paper is to provide fundamentals of few reversible logic gates, the comparison between their operations and their applications.