If you've been taken by Craig Robertson's Staten Island Slide, or by the traditional Hawaiian Song He'eia, which was the favorite surfing spot of the last king of Hawaii, then you've fallen in love with a ukulele! Over the years, the popularity of this small instrument has surged repeatedly, and it's going through another one of those happy cycles. It's smaller than a guitar, and it only has four strings instead of the guitar's usual six. Just what is this instrument, and where did it come from?

Nobody's really certain who actually invented the ukulele. We do know that it became widely known when Portuguese immigrants brought it to Hawaii in the late-1800s. The Portuguese developed it from a similar instrument called the cavaquinho.

It became an important part of Hawaiian musical culture when strolling street singers used this tiny instrument as an accompaniment. The island king mentioned above was David Kalakaua, who reigned from 1874 through 1891, and once he fell in love with it, he demanded that it be integrated into royal performances on a regular basis.

Once the ukulele crossed over into American culture, before Arthur Godfrey ever strummed a chord, it was used generously in early jazz music, although it was replaced in later years by the guitar.

There are four basic sizes of ukulele, although you will find some variations. You'll be choosing one of these:

• The soprano ukulele was the first one developed, and it's the smallest of all the varieties at 21 inches (53 cm). It's also the highest pitched. Most people choose this size for their very first. It's a great way to have stringed-instrument capability that's small enough to carry along anywhere!

• The alto, or concert, ukulele is somewhat larger at 23 inches (58 cm). The sound is slightly fuller.

• The tenor ukulele is the next up in size at 26 inches (66 cm). It provides the capability of rich resonance without string buzz. Some tenor ukuleles come with six or 8 strings instead of four. Many true ukulele enthusiasts claim this type as their favorite.

• The baritone ukulele, at 30 inches (76 cm) is best for larger hands, and while it retains its characteristic ukulele sound many people buy it because it sounds more like an acoustic guitar. And it's easy to switch from this instrument to a guitar due to playing the same chords.

• There are a few hybrids, such as the banjo ukulele, which combines ukulele frets with the banjo body, or the harp ukulele, much like a harp guitar. You can also find very tiny so-called sopranino ukuleles and the larger bass ukuleles.

A true ukulele is made from wood, with the cheaper ones made from laminated wood or plywood and the more expensive models ranging from spruce to mahogany to your top-of-the-line model, Hawaiian koa wood. It has frets like a guitar, and most people like the nylon-type Aquila strings.

Because the strings are shorter than those on a guitar, you need to give them a lot of play to get them properly stretched. Once they're stretched, your ukulele will stay pretty much in tune, and you don't need to have the most expensive model to get a good sound. People who don't play it often don't break in the strings properly, and you will hear them complain that their instrument does not stay in tune. They just need to play it more!