The definition of unemployment that is used by the UN is the ILO definition, this covers those that are out of work, want a job, have actively sought work in the previous four weeks and are available to start work within the next fortnight; or out of work and have accepted a job that they are waiting to start in the next fortnight. The most common form of unemployment that affects the UK is cyclical unemployment. This occurs when there is an economic downturn such as a recession. As there is reduced demand for goods and services, firms do not require as many workers to fulfil customer demands and so people are laid off. As more people become unemployed the ability of consumers in general to purchase goods and services is diminished as they may be dependent on social security payments and saving and thus reduce consumption. A cause of unemployment which affects Northern Ireland, in particular, is structural unemployment, where an economy moves away from one industry ( in Northern Ireland's case shipbuilding) and towards another such as tourism.There are few transferable skills and so this leaves a large number of people unable to find work in the new sector. The third cause of unemployment is voluntary, some people may choose not to work for reasons such as caring for a relative, minding children or simply the cost of commuting to a place of work makes it not worthwhile to take a job.