A Call Option is security that gives the owner the right to buy 100 shares of a stock or an index at a certain price by a certain date. That "certain price" is called the strike price , and that "certain date" is called the .
A call option is defined by the following 4 characteristics:
There is an underlying stock or index
There is an expiration date of the option
There is a strike price of the option
The option is the right to BUY the underlying stock or index. This contrasts to a put option, which is the right to sell the underlying stock