From Joomla! Documentation

What we are seeking for this page is:-

  • a general description of what a Captcha is and when and why it would be useful.
  • some background on pros and cons so that people can make an informed decision on whether to install a Captcha on their Joomla site.
  • a link to the Captcha section on the JED, but not to any specific extension. This would be acceptable: [1].