A verification code is a security protection method used by form owners to avoid Internet robots from abusing and spamming their web forms. There are different verification code types, but the most common used is CAPTCHA and Smart Captcha. A random generated code appears in an image above a textbox where the visitor has to type the exact code in order for the form information to be sent. Each time the form is accessed, a different code will appear.
Owners can deactivate the verification code of their web forms, although this would increase the vulnerability of the forms to spamming attacks. The verification code is linked to the entire form, so if it is not completed properly, the information of the web form will not be sent.