The voluntary sector includes organisations which are not-for-profit, and are run to benefit or help particular groups or sections of society. Most of them will be registered charities who rely heavily on the time and effort of volunteers. Whilst some small charities will run entirely with voluntary effort, larger organisations also need paid staff in various roles. Some of these charities will even be contracted to carry out work for other organisations, for example children's charities which provide services for children and young people on behalf of local authorities. Staff will be expected to demonstrate a high level of commitment to the aims of the organisation, and salaries can often be lower than elsewhere.