Here is a slightly adapted extract from my book:
The ukulele is a small guitar with four nylon or gut strings. Its strings are tuned in a similar way to the first four strings of a guitar, but at a higher pitch. A significant difference is that its tuning is re-entrant, that is, the fourth string is tuned high rather than low as it would be on a guitar – but more about that interesting fact in my book.
Many books trace the recent origin of the ukulele to Hawaii in the late nineteenth century. Stories tell of Portuguese immigrants to Hawaii who developed the ukulele in 1879 from a instrument called a Machette. I like to think of this as a rediscovery. One type of sixteenth century guitar was ukulele-like. These guitars were small, had four courses of strings that were sometimes tuned, respectively, G C E A – a popular tuning for modern ukuleles.
The first western reference to the word ‘ukulele’ that I can find is by the Rev. Henry T. Cheever. Cheever tells how his sleep was horribly disturbed by ukuleles – not the musical instrument, but the insect – fleas! The name somehow was given to the small guitar around 1879. The instrument (and, I suppose, the insect) is pronounced ‘Oo-coo-lay-lay’, but I still say ‘You-ku-lay-le’ myself.
Around 1915, the ukulele (the instrument) was introduced to mainland USA, at least this was the time the ukulele was really noticed there. By the 1920s it had become very popular, being promoted around the world by professional entertainers. During the 1920s, if a man was serious about a woman, he might have bought her a ukulele. And, if there were no serious men about, a woman could always buy a ukulele for herself. People like May Singhi Breen (died 1970) and Roy Smeck (1900-1994) played intricate melodies on the uke, and encouraged others to see it as a solo instrument too. Jim Beloff notes that both Jesse Kalima (1920-1980) and Eddie Kamae are credited with developing styles of chord soloing – where the tune is played as the chords are strummed or plucked.
The little ukulele was ‘big’ again in the 1940s and 1950s, survived the surprise of Tiny Tim in the 1960s, and now, in the early 21st century, is becoming an instrument of influence once more. My little book is a humble effort to promote the playing of tunes on the ukulele.
 See, for instance, John King and Jim Treanquada, “A new history of the origins and development of the ‘ukulele, 1835-1915”, The Hawaiian Journal of History 37 (2003), pp.1-32.
 Eg., Michael Fink, “Renaissance guitar music for the classical guitarist”, http://www.lgv-pub.com/Essays/Ren_Guit_Mus_-_Class_Guit.pdf (accessed 5 April 2009).
 The Library of Congress holds a photograph from 1926 of five happy young women with ukuleles, but I cannot say how they got them. Photograph at http://hdl.loc.gov/loc.pnp/npcc.16039 Library of Congress, Prints & Photographs Online Catalog, http://lcweb2.loc.gov/pp/pphome.html (accessed 5 April 2009). I first found this picture on http://www.shorpy.com, a site that holds a wealth of vintage photography. (See Happy Girls with Ukuleles — 1926)
 Jim Beloff, The ukulele: a visual history (California: Miller Freeman, 1997), p.51.