The word CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart"
Unfortunately there is software, used by spammers, which automatically fills in contact and registration forms on web sites. A CAPTCHA system is designed to prevent this software from automatically submitting the form by requesting an action to be performed, which only a human could do. For more info on CAPTCHA feel free to visit the Wikipedia CAPTCHA Page
There are many different types of CAPTCHA systems in use, like typing a word which has been distorted in some way.
At gasworld we do not want our directory to be littered with bogus entries, some of which can be quite offensive. Although we do monitor the registrations, we cannot do so 24 hours a day.
For this reason we have implemented a simple CAPTCHA system which is very simple for our users to use, to reduce the inconvenience it might cause.