This form uses a Captcha - a type of challenge-response test used to determine whether the user is human.  This helps to prevent the form from being abused by spambots by asking you to input the sequence of letters and numbers shown in the graphic.
Without the captcha it would be possible for nefarious types to fill in the form automatically in the hope of advertising their wares and sites.
There are five characters consisting of lower-case letters and numbers. Required fields are starred.