sentences:  Ideally, this strategy should be used when either A) the implied volatility of the options expiring in a particular month has recently moved sharply higher and is now beginning to decline, or B) the trader believes for whatever reason that the underlying market of the option(s) will move steadily in his favor during the life of the option.The trader will use call options in this strategy if he believes the underlying market will move steadily higher, and put options if he believes the market will move steadily lower.In the case of call options, the trader will buy some number of options having striking price X and write (sell) a larger number of options having striking price Y, where Y is greater than X.