This book is about the estimation of market volatility (or variance of returns of an asset) is a crucial issue in modern applied finance. The measure of volatility and good forecasts of future volatility are crucial for implementation, evaluation of asset and derivative pricing of asset. In particular, volatility has been used in financial markets in assessments of risk associated with short-term fluctuations in financial time-series. Volatility has a key role to play in the determination of a risk and in the valuation of options and other derivative securities. Exercises and examples are provided to make understanding of the book easier. Other models are also included to act as prerequisite knowledge to the developed models herein.