These are the settings to determine if an anti-spam measure will be employed on the web site (not to be confused with security settings). This can be used to help prevent your web site being used to flood the world with spam. Currently the only method is using reCAPTCHA.
To activate the anti-spam measures, you must 1) turn the Use Anti-Spam measures setting on and 2) select and configure the Anti-Spam Method.
In order for reCAPTCHA to work with forms, you need to select reCAPTCHA as the anti-spam method, and insert your private and public keys.
If you do not have those keys, reCAPTCHA is free and you can sign up for an account here: https://www.google.com/recaptcha/admin
You can also choose some various display themes for reCAPTCHA. When configured, the forms should display a reCAPTCHA area that looks similar to this. reCATHCA is displayed before the user presses the submit button on the form..