If a studio or production company (or even a private party) decides your idea is worth developing, they might offer to option your story. An option is a comparatively small amount of money given to a writer in exchange for exclusive rights to your script for a specified length of time. Rather like a lease on a car with an option to buy, it indicates that a producer has faith in your material, but either doesn't have the kind of funding required to purchase your script outright or is unsure of her ability to get a green light to begin development.
Option deals can be beneficial for all concerned parties. Producers with limited funds can get access to new material, while providing a way into the business for fledgling writers and filmmakers. As a filmmaker, you can pursue an option deal if you have the rights to your work.
In essence, a producer is paying for permission to shop your script to studios or other production entities. If someone agrees to produce it, the producer pays you the full amount agreed upon to purchase your script. If no one wants it before the specified time limit, the rights revert back to you, and you keep the option money.
An example of this is screenwriter Richard Hatem, who read the book