What does the term "camera-ready" mean and why is it used?
From the Wikipedia article entitled "Camera-ready":


  The term camera-ready was first used in the photo offset printing
  process, where the final layout of a document was attached to a
  "mechanical" or "paste up". Then, a stat camera was used to photograph
  the mechanical, and the final offset printing plates were created from
  the camera's negative.
  
  In this system, a final paste-up that needed no further changes or
  additions was ready to be photographed by the process camera and
  subsequently printed. This final document was camera-ready.
  
  In recent years, the use of paste-ups has been steadily replaced by
  desktop publishing software, which allows users to create entire
  document layouts on the computer. In the meantime, many printers now
  use technology to take these digital files and create printing plates
  from them without use of a camera and negative. Despite this, the term
  camera-ready continues to be used to signify that a document is ready
  to be made into a printing plate.