The Visible light communication (VLC) is a novel topology seeks to improve the large, unused visible light spectrum of 400-800THz. The VLC technique employs a non-radio frequency, which is converted and restricted from telecommunications licenses, to meet an urgent need. Flicker is a serious issue because light is modulated at such a high rate, which can harm the human eye. Dimming is also a problem in indoor environments, in which an amount of light are required to be regulated according to the needs of the user. The rise time as well as non- linearity of LED creates problem in modulation. Hence, to overcome these issues, many modulation techniques has been employed in VLC. In this paper, a survey is carried out regarding the various modulation techniques used in VLC, in order to find the optimal one.