必需品在经济学概念中，被认为是缺乏弹性的需求。

如包括食物、燃料、衣服、公用事业和医疗服务等都属于必需品。

1. ↑ 居民生活必需品调查 中国人爱电视美国人恋汽车 中国经济网 2014-06-01

In economics a necessity good is a type of normal good. Like any other normal good, when income rises, demand rises. But the increase for a necessity good is less than proportional to the rise in income, so the proportion of expenditure on these goods falls as income rises. This observation for food is known as Engel's law. The income elasticity of a necessity good is thus between zero and one.