Abstract: Proper choice of econometric model for characterizing stochastic volatility is essential for different financial problems like prediction, VaR estimation, option pricing etc. This paper reviews the stochastic volatility models (SVMs) with an emphasis on realized volatility literatures. SVMs evolved and characterized during last two decades are considered for comparison with respect to their evolution and contributions. This work uses unified mathematical notations for explaining the models from diversified approaches in the supporting literature. The present work summarizes estimation techniques, and advocates the use of sophisticated filtering techniques for different types of state and parameters of SVMs.