Option is the right to buy or sell a security in a period time. There are generally two kinds of options, call option and put option. Call option gives the right to buy the security and put option gives the right to sell the security. There are basically three types of options, American option, European option, and Bermuda option. American option holders can execute the option before the determined time, European option holders can only execute it on the promised day, and Bermuda options have several time points to execute the options.