{I really like this challenge arena and plan to participate.} Cool! {Can I have some specifics?} CHeck the FAQs. Essentially anyone can issue a challenge of either a general or specific nature at any time. There is also a monthly challenge that is always general. With a general challenge, anyone can participate. With a specific challenge, you either target one person (i.e. the infamous Triangle Challenges), or a group of people or even a Team (as per the Team Challenges of, February, IIRC). Check the Archives for examples of these. { How long do we have to submit a picture? } Depends on the challenge. Some are very open ended (whenever it's finished), some are specific (by next Friday!) and the monthly ones are due on or before midnight on the last day of the month. {Who judges it?} Depends on the challenge - either the person issuing it or anyone visiting this forum. {What does the winner get?} Again depends on the challenge. For the monthly ones, the winner gets the right to issue the NEXT month's challenge, for example. Some challenges also net award graphics, and some have prizes, but most of the latter are done in the Contests forum not here.