Web sites that accept postings from the public, like this wiki, are often abused by spammers who use automated tools to post their links to many sites. While these spam links can be removed, they are a significant nuisance.
Sometimes, especially when adding new web links to a page, the wiki may show you an image of colored or distorted text and ask you to type the words shown. Since this is a task that's hard to automate, it will allow most real humans to make their posts while stopping most spammers and other robotic attackers. Another test is to ask you to type in the answer to a simple arithmetic problem. You must have cookies enabled in your browser, otherwise your answers to these tests will not be accepted.
Unfortunately this may inconvenience users with limited vision or using text-based or speech-based browsers. At the moment we do not have an audio alternative available. Please contact the site administrators for assistance if this is unexpectedly preventing you from making legitimate posts at the Commons:Help desk. (If you are giving a correct answer that is not being accepted, please provide details of the problem.)
Hit the 'back' button in your browser to return to the page editor.