Designation of workers by collar color

Collar color is a set of terms denoting groups of working individuals based on the colors of their collars worn at work. These can commonly reflect one's occupation within a broad class, or sometimes gender.; at least in the late 20th and 21st Century these are generally metaphorical and not a description of typical present apparel. For the two terms of longest use, white-collar workers are named for the white-collared shirts that were fashionable among office workers in the early and mid-20th century. Blue-collar workers are referred to as such because in the early 20th century, they usually wore sturdy, inexpensive clothing that did not show dirt easily, such as blue denim or cambric shirts. 
Various other "collar" descriptions exist as well, although none have received the kind of broad use in American English as the traditional white-collar/blue-collar distinction.
White collar.
The term "white-collar worker" was coined in the 1930s by Upton Sinclair, an American writer who referenced the word in connection to clerical, administrative and managerial functions during the 1930s. A white-collar worker is a salaried professional, typically referring to general office workers and management.
Blue collar.
A blue-collar worker is a member of the working class who performs manual labor and either earns an hourly wage or is paid piece rate for the amount of work done. This term was first used in 1924.
Pink collar.
A pink-collar worker is also a member of the working class who performs in the service industry. They work in positions such as waiters, retail clerks, salespersons, and many other positions involving relations with people. The term was coined in the late 1970s as a phrase to describe jobs that were typically held by women; now the meaning has changed to encompass all service jobs.
Other classifications.
There are a number of other terms used less frequently, or which translate to English from common use in other languages. These categories include: