Unfortunately we receive a large number of spam emails through our Contact Us form, which are generated automatically by robot programs which search the internet for suitable forms to attack. Image Verification is a security test to determine whether or not the user is human. This will ensure that only human visitors will actually submit the form, and not spamming 'bots' that are browsing the web from site to site. These 'bots' search the Internet by following links from page to page and collect email addresses listed on websites, submit contact forms, or even try to break passwords by trying to login over and over again with computer generated passwords.
Fortunately, it is more difficult for a non-human ( e.g. computer program ) to extract a word or a combination of letters and numbers from an image, if the letters and numbers are not all of the same size and of similar font. This is why the Image Verification security method is used to try and ensure that only people can submit a form.