In the current scenario of delivering therapeutic agents to the target site requires an efficient drug delivery carrier which can deliver the drug only on the site of action in a sustained and controlled manner. Among many such carriers, microspheres fulfill all the parameters for an potent drug carrier. Microspheres are defined as free flowing powders of spherical shape, consisting of proteins or synthetic polymers, which are either biodegradable or non-biodegradable in nature and ideally having a particle size ranging from 1-1000 μm. The main aim of such novel drug delivery system is to overcome the limitations of conventional dosage forms and providing more patient compliance, increase bioavailability and more specifically targeted delivery of drugs or other active agents. This review articles deals with the ideal characteristics, types, methods of preparation, their characteristics evaluation, in vitro-in vivo correlation and applications of microsphere as drug carrier. There are various methods available today for the preparation of microspheres with the goal of achieving reproducibility and consistency with good entrapment efficiency.