Content-based image retrieval is currently a very important area of research in the area of multimedia databases. Plenty of research works had been undertaken in the past decade to design efficient image retrieval techniques from the image or multimedia databases. Although large number of indexing and retrieval techniques have been developed, there is still no universally accepted feature extraction, indexing and retrieval techniques available. In this paper, we present an up-to-date review of various content-based image retrieval systems. Since the volume of literature available in the field is enormous, only selected works are mentioned.