Zero hours contracts are casual contracts which allow employers to hire staff with no guarantee of work. Some casual contracts will have a minimum number of hours, such as eight or 16 hours, but hours and days of work can vary dramatically from week to week. Employees work only when they are needed, often at very short notice. In the worst examples employees are required to be available to work whenever needed and precluded from working for anyone else but guaranteed absolutely nothing. This is the kind of contract that many people are now calling to be banned.