A biometric system has become popular research topic over past decades for achieving high security in various areas. Several biometric methods are used based on physiological and behavioral features of human, among which IRIS recognition system is gaining more attention due to its properties such as reliability, uniqueness, stability, noninvasive nature etc. Iris recognition system consists of four main steps: iris localization, normalization, feature extraction and iriscode matching. This paper gives a review of some iris recognition system given by various researchers to extract unique features of iris(freckles, coronas, stripes, crypts, furrows etc.) to get high recognition rate. Comparison table of techniques of different iris recognition algorithm is also presented in brief.