This paper is a result of the literature survey in the field of Augmented Reality and helps in understanding the concept behind Augmented Reality. It includes the methodologies involved in the implementation of Augmented Reality. Marker-less and Digital Markerbased AR, being the two ways through which AR can be implemented, have been explained in detail in this paper. The detailed steps involved in the implementation of Marker-less AR -Edge Vectorization of Objects using CVSDF graphs, Detection of objects, Recognition of Variation of Objects, Calibration have been covered in detail. An image processing algorithm is used to detect visual code markers. Features of these fiducial markers and the process involved in detecting them have been explained in detail.