The invention relates to an umbrella, particularly a sun umbrella or rain umbrella, comprising a holding structure and an umbrella roof attached thereto by means of a joint, the joint being able to be locked by means of a cable or Bowden wire running through at least one part of the holding structure, characterized in that the joint is designed as a purely rotating joint, wherein an engagement element located on the umbrella roof is connected to the cable or Bowden wire or is otherwise mechanically operationally connected thereto, in order to releaseably engage in a segment of the joint associated with the holding structure to lock the joint.