Microplastics are small plastic particles, typically less than 5 mm in size, that pose serious environmental concern and human (and animal) health risks worldwide. They are classified based on type, size, shape and chemical composition. They are divided into primary microplastics, which are purposefully manufactured as small plastics (e.g., microbeads and nurdles), and secondary microplastics, formed by the biotic or abiotic degradation of larger plastics. They are further categorized based on their size into mesoplastics, microplastics, and nanoplastics. Classification based on shape include fragments, fibers, pellets, foams, films and beads. They are also classified as thermoplastics, thermosetting plastics, elastomers and biodegradable plastics based on their chemical composition. Microplastics are formed from a wide variety of sources and enter the living system via ingestion, inhalation or dermal contact, and distribute via circulatory system. They pose varying health risks through physical blockages, chemical toxicity, bioaccumulation and biomagnification. They have significant impact on various tissues and organ systems. They persist in ecosystem for longer period of time, accumulate in food chain, and pose risks to terrestrial and aquatics animals. They also effect the environment by disrupting soil structure and ecology, and interact with organic pollutants, heavy metals and pathogens. The control measures include reduce plastic manufacture/use, improved waste management, regulative and legislative measures, public awareness and education, and innovative policies.