Now is the age of high-tech research and development. Different types of fibers have been produced in the last decades for the benefit of human needs. Core-shell nanofibers are a revolutionary development in the field of science and technology. Preparation of nanoscale fibers in a core-shell configuration, using two dissimilar materials, via a novel technique of electrospinning has presented unusual potential for use in many novel applications. The studies have addressed issues related to the technology involved and examined the suitability of the technique for producing unique nanoscale morphologies involving variety of materials. Numerous studies have been published on the preparation of core-shell nanofibers by electrospinning process for developing novel structures for new applications. No major review of the co-axial electrospinning process has appeared to the knowledge of the authors but is needed in order to develop a fuller understanding of the status of work in this field. After a brief introduction to the conventional electrospinning process, this paper focuses on the preparation and uses of core-shell fibers by electrospinning studies published to date. It attempts to categorize them in terms of the approaches adopted, and highlights the knowledge gained with respect to the material and process parameters that impact the size and the uniformity of the core-shell nanofibers obtained.