The quality of captured images will be highly affected by an abnormal weather like rain or snow. Such bad weather conditions can degrade and corrupt the performance of various outdoor vision systems like CCTVs, traffic cameras etc. Even if many bad weather conditions can affect the quality of captured images, rain affects the image in a more negative way because, it is observed as bright streaks. Because of the negative effect of rain on outdoor vision systems, rain removal is an important problem. Detecting rain streaks accurately is a difficult task since rain has no particular location in an image. Rain removal has been an active research topic over many years and several techniques has been proposed. From all these studies, rain removal from an image can be classified into four main categories. The first category is simply filtering based whereas the second category builds models for rain streaks. In the third category, a 2-step processing is performed for rain removal and in the fourth category, deep learning techniques are used. So, in this paper, we have done a detailed study on the effects of rain on images and various rain removal methods.