Although many users find Captcha annoying and irritating the use of Captcha test as a mean of spam prevention becomes more and more popular since there is no other absolute alternative way to stop those bots from getting hold over online blogs, forums and other social platforms.

Dal Net is just one example.
As was written on  IRC-Junkie website,  Dal Net, one of the IRC (Internet Relay Chat) networks has just added a “text Captcha” to their registration process – this text captcha present a question that has to be answered by human user (instead of deciphering alpha numeric distorted letters as requested by the original captcha we are all familiar with). The question could be something like “Mark’s name is?” and the answer should be:
NickServer/Registraion<password><email>mark.

The questions will be, of course, changed every week.

The reason they’ve added Captcha system is because they have noticed “increases in bots getting nicks and channels, holding them, and never releasing them… and it’s not fair to the average person that a bot gets a nickname before human does”.

By using Captcha they hope to ensure their services (such as nicknames, channels, chat rooms and so on) will be used by human beings first and not by bots.