MEMS - Micro electro mechanical systems. It refers to machines with moving parts smaller than a human hair that contain both electrical and mechanical components on silicon. Also referred to as Microsystems, microstructures, microstructure technology (MST) and mechatronics. Micro electro mechanical Systems (MEMS) have gained acceptance as viable products for many commercial and government applications. This paper gives a brief review of history and components of MEMS. This paper will discuss current and future MEMS applications. It then gives the fabrication processes of MEMS. Further this paper discusses about the MEMS achievements, challenges and requirements. Next it discusses the future form of MEMS. Lastly it concludes saying that MEMS have enough potential to establish a second technological revolution of miniaturization that may create an industry that exceeds the IC industry in both size and impact on society