The term white-collar worker refers to a person who performs professional, managerial, or administrative work, in contrast with a blue-collar worker

Blue-collar worker

A blue-collar worker is a member of the working class who performs manual labor. Blue-collar work may involve skilled or unskilled, manufacturing, mining, construction, mechanical, maintenance, technical installation and many other types of physical work...

, whose job requires manual labor. Typically white collar work is performed in an office or cubicle.
The term refers to the white dress shirt

Dress shirt

A shirt, or dress shirt in American English, is a garment with a collar, a full-length opening at the front from the collar to the hem, and sleeves with cuffs. Shirts are predominantly used by men, since women usually wear blouses...

s of male office workers common through most of the nineteenth and twentieth centuries Western countries as opposed to the blue shirts, uniforms or cover-alls of manual or service workers.

The term "white collar" is credited to Upton Sinclair

Upton Sinclair

Upton Beall Sinclair Jr. , was an American author who wrote close to one hundred books in many genres. He achieved popularity in the first half of the twentieth century, acquiring particular fame for his classic muckraking novel, The Jungle . It exposed conditions in the U.S...

, an American writer, in relation to modern clerical, administrative and management workers during the 1930s, though references to "easy work and a white collar" appear as early as 1911.