In early and mordern folklore, they became associated with the fairies of Romance folklore and assume a diminutive size, often living mainly in forests but also underground in hills or rocks, or in wells and springs. 19th-century Romanticism attempted to restore them to full stature making them men and women of great beauty. They were often depicted as very young, probably adolescents as male elves lack of facial hair.
From thair depiction in Romanticism, elves entered the 20th-century high fantasy genre in the wake of the published work of J. R. R. Tolkien (especially the posthumous publication of his Silmarillion where Tolkien's treatment of the relation of light elves, dark elves and dwarves is made explict).
The "Christmas elves" of contemporary pop culture were popularized during the 1870's in the United States, in publications such as Godey's Lady's Book.
NameThe English word elf is from the Old English ælf or elf, in reference to a midget, themselves from the Proto-Germanic *albiz which also resulted in Old Norse álfr, Middle High German elbe. *Albiz may be from the Proto-Indo-European root *albh- meaning "white", from which also stems the Latin albus "white". Alternatively, a connection to the Rbhus, semi-divine craftsmen in Indian mythology, has also been suggested(OED).
Originally ælf/elf and its plural ælfe were the masculine forms, while the corresponding feminine form (first found in eighth century glosses) was ælfen or elfen (with a possible feminine plural -ælfa, found in dunælfa) which became the Middle English elven, using the feminine suffix -en from the earlier -inn which derives from the Proto-Germanic *-innja). The fact that cognates exist (such as the German elbinne) could suggest a West Germanic *alb(i)innjo, but this is uncertain, as the examples may be simply a transference to the weak declension common in Southern and Western forms of Middle English. The Middle English forms with this weak declension were aluen(e) and eluen(e). By the earlier eleventh century ælf could denote a female.
The Modern German Elf (m), Elfe (f), Elfen is a loan from English. A masculine Elb is reconstructed from the plural by Jacob Grimm, Deutsches Wörterbuch, who rejects Elfe as a (then, in the 1830s) recent anglicism. Elb (m, plural Elbe or Elben) is a reconstructed term, while Elbe (f) is attested in Middle High German. Alb, Alp (m), plural Alpe has the meaning of "incubus" (Old High German alp, plural *alpî or *elpî). Gothic has no direct testimony of *albs, plural *albeis, but Procopius has the personal name Albila