Topological defects in cosmology

We present a brief review of topological defects and the role they play in cosmology. Though there is no compelling evidence yet of the existence of these topological defects in the Universe, still, this topic has received much attention recently due to important implications topological defects have for cosmological models [1]. In the following, we first give a physical description of topological defects in detail using simple examples. Then we explain how these defects are thought to arise in the early Universe and various consequences of their existence for the Universe [1,2].