A common security measure on website forms is to use CAPTCHA codes, where distorted letters or some other form of test is displayed to check that the person submitting data is not a spam robot. The form that we have been building to accept visitor-submitted book reviews could benefit from this type of technology to avoid weeding through unwanted entries.
This recipe shows how to integrate Google's reCAPTCHA service in our book review submission form. If you prefer using a local CAPTCHA script to avoid being dependent on an online service or to be sure that your form can be used in all countries, jump to the next recipe, titled Using a local library to implement a CAPTCHA on user forms.
