The standard western concert flute which are reviewed on this site have 16 holes. This helps it cover three octaves and all the half notes in there. The most common kind is the C-flute, so called because the lowest note is the Middle C.
The system of the Western 16 hole flute was designed halfway through the 19th century by Theobald Boehm. Flutes made today usually conform to this ‘Boehm system’ with only minor refinements.
The Western concert flute is a 16 hole side-blown or transverse flute that makes a sound when one blows OVER (instead of IN) the hole. The player blows “across” the embouchure hole, in a direction perpendicular to the flute’s body length.
Compare this to the recorder: the flute most of us learn to play as kids. I did too and loved the sound, honestly. However, later on I learned that the plastic variety mostly used in cheaper music lessons truly sounds awful. So do invest in a wooden recorder if you expect your child to have any musical sense at all. An aunt of mine plays the recorder professionally – it is a larger bass flute. Recorders can have up to 9 holes and usually cover only two octaves, though recorders with a range of 3 octaves have been produced.
This article would not be complete without mentioning the piccolo: a 16 holed flute that starts an octave higher than the standard concert flute. It is a half-sized flute with the same fingering as the standard transverse flute.
Piccolo’s are not recommended for a beginner player, due to the difficulty in fingering as compared to the ordinary flute.