The new technology of video compression standard - High Efficiency Video Coding has got more popularity as the world is going completely digital through video applications like Internet streaming, Digital video broadcasting, Video conferencing, Video surveillance, etc. So it is necessary to have very high video quality with reasonable complexity. This is achievable with In-Loop Filter of HEVC decoder containing two filters put one after the other, Deblocking Filter and Sample Adaptive Offset Filter. These filters together will build the visual and objective quality of the video. This paper helps in understanding the basics of the filters and summarizes the important methods, techniques proposed by various authors.