This article it's a guide on how to set up Google reCaptcha to reduce spam.
NOTE: Before completing this step, FIRST connect the live domain name. Please see: How To Move Your Site To Your Live Domain.The website needs to have the reCAPTCHA key set up in order to have the public forms prevent SPAM. As Google describes it, "reCAPTCHA is a free service that protects the website from spam and abuse. reCAPTCHA uses an advanced risk analysis engine and adaptive CAPTCHAs to keep automated software from engaging in abusive activities on the site. It does this while letting valid users pass through with ease."
For this reason, if the reCAPTCHA keys have not yet been set up the checkout pages won't be available and will display the following message: