Valet and varlet are terms for male servants who serve as personal attendants to their employer. In the Middle Ages and Ancien Régime, valet de chambre was a role for junior courtiers and specialists such as artists in a royal court, but the term "valet" by itself most often refers to a normal servant responsible for the clothes and personal belongings of an employer, and making minor arrangements.
In the United States, the term most often refers to a parking valet.
In English, valet as "personal man-servant" is recorded since 1567, though use of the term in the French-speaking English medieval court is older, and the variant form varlet is cited from 1456 (OED). Both are French importations of valet (the "t" being silent in modern French) or varlet, Old French variants of vaslet "man's servant", originally "squire, young man", assumed to be from Gallo-Romance Vulgar Latin *vassellittus "young nobleman, squire, page", diminutive of Medieval Latin vassallus, from vassus "servant", possibly cognate to an Old Celtic root wasso- "young man, squire" (source of Welsh gwas "youth, servant", Breton goaz "servant, vassal, man", Irish foss "servant"). See yeoman, possibly derived from yonge man, a related term.
The modern use is usually short for the valet de chambre (French for "valet of the chamber", in modern terms the bedroom, though not originally so), described in the following section.
Since the 16th century, the word has traditionally been pronounced as rhyming with pallet, though an alternative pronunciation, rhyming with chalet, as in French, is now common. The Oxford English Dictionary lists both pronunciations as valid.
A valet or "gentleman's gentleman" is a gentleman's male servant; the closest female equivalent is a lady's maid. The valet performs personal services such as maintaining his employer's clothes, running his bath and perhaps (especially in the past) shaving his employer.