Children around the world are routinely engaged in paid and unpaid forms of work that are not harmful to them. However, they are classified as child labourers when they are either too young to work or are involved in hazardous activities that may compromise their physical, mental, social or educational development. The prevalence of child labour is highest in sub-Saharan Africa. In the least developed countries, nearly one in four children (ages 5 to 14) are engaged in labour that is considered detrimental to their health and development.