A captcha is an acronym for “completely automated public Turing test to tell computers and humans apart - in other words a type of challenge-response test used to determine whether or not a computer user is human (or another computer).
From the Wikipedia entry on Captcha’s:
A common type of captcha requires that the user type the letters of a distorted and/or obscured sequence of letters or digits that appears on the screen. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, a captcha is sometimes described as a reverse Turing test
Recently, I have seen several bloggers install captcha’s as a way to try to stop comment spam on their site - guys, captcha’s are lame.
Why are captcha’s lame? Captcha’s are lame because:
- they force the burden of work back on your commenter and pushing extra work on your readership displays a lack of respect
- they show you are too lazy to properly secure your blog against comment spam (using blacklists, .htaccess, number of links, etc.) and most importantly,
- they discriminate against partially-sighted readers
There are many good anti-comment spam tools and procedures available, don’t use captchas.
Bad Behaviour updated
Via James comes news that the anti-spam plugin Bad Behaviour has been updated to version 2.0.4 - if you use this plugin (and you should if you have a php based site) then you need to get the most up-to-date version.
You can download Bad Behaviour here.