The values of the parameters r, t, St, T , and K used to price a call option via the Black-Scholes formula can be easily obtained from market data. Estimating the volatility coefficient σ can be a more difficult task, and several estimation methods are considered in this section with some examples of how the Black-Scholes formula can be fitted to market data. We cover the historical, implied, and local volatility models, and refer to [25] for stochastic volatility models.