Each kata is crafted for and by the community. Kata are created by other users rewarded with kata authoring privilege. When a kata is published by an author (or Sensei), it will go into a beta process where the community can help test and provide quality assurance feedback and cast a vote for its difficulty ranking. The feedback during this process is vital to making sure all kata are of the highest quality.
Not every user is able to perform a full review of a beta kata, but every user can help in some way! Users are strongly encouraged to participate in the beta evaluation of kata awaiting their approval. For more details, see Curating of a Kata.