The ukulele is a string instrument belonging to the plucked lute family, subdivided into the guitar family. A ukulele generally has four nylon strings. The tuning is related to that of the guitar; the ratios are the same as the highest four strings of the guitar, but the top string is tuned an octave higher. The most popular tuning today is g’c’e’a’, also known as C tuning. There is also the D tuning, a’d’f#’b’, in which all strings are tuned a whole tone higher. Although the D tuning used to be more standard (and still is in some countries), both tunings have always existed side by side.