The working class is a subset of employees who are compensated with wage or salary-based contracts, whose exact membership varies from definition to definition. Members of the working class rely primarily upon earnings from wage labour. Most common definitions of "working class" in use in the United States limit its membership to workers who hold blue-collar and pink-collar jobs, or whose income is insufficiently high to place them in the middle class, or both. However, socialists define "working class" to include all workers who fall into this category; thus, this definition can include almost all of the working population of industrialized economies. Source: Wikipedia (en)