This technical note addresses the basics of risk measure for options. It introduces the different risk measures for options: Delta, Gamma, Vega, Rho, and Theta. Although the note focuses primarily on price risk (Delta) and the Delta risk (Gamma), it does address volatility risk (Vega), interest-rate risk (Rho), and time decay (Theta). In addition to providing derivations and basic calculations, the note provides a full description of Delta hedging.