This simple hack is meant as a replacement for the default CAPTCHA system in vBulletin. There are two main reasons one might want to do this: firstly, new technology is constantly being developed to crack CAPTCHA images and make spam accounts anyway, and secondly, the more secure the CAPTCHA, the more difficult it is for genuine users to tell what the numbers in the image are. There is also the issue of visually impaired users, and the fact that not all servers are capable of generating CAPTCHA images.
NoSpam! – an alternative to CAPTCHA images
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