There is new technology for user verification that is planned to take over from the conventional ReCaptcha tech that uses an image of words that the user has to type into a text box to pass verification and enter a comment on a blog or perform other tasks that require anti-spam countermeasures to stop the omnipresent spam bots from swamping the website. The new technology is called playthrough and uses a simple game that the user plays, such as putting certain items into a refrigerator, and this allows user verification without having to decipher text that is sometimes very hard to read, necessitating the use of the blue refresh button to find a new Captcha challenge that is not so hard for a human to read. This could be a worthwhile alternative, there are not too many other ways to verify a human website visitor is not a spambot. In the future computers will be able to crack any ReCaptcha task and there will need to be a better spam countermeasure that can stop spammers but is not too hard for a human to solve. I find that the Google ReCaptcha system works perfectly and I am quite happy with it. For a PHPBB message board, the ReCaptcha plugins is also very effective for stopping spam that would otherwise swamp the board and clog up the database with useless spam messages. It is possible that some other method of verification could appear out of nowhere and take us all by surprise.
Something that a computer can not solve would be perfect, who knows what the future will bring.