Flutes are different than most woodwinds in that they don't have reeds. The column of air inside a flute is set in motion by the player blowing across or into an opening. The orchestral flute is a "transverse" or horizontally held flute and the player blows across the opening just the way you can blow across the top of a bottle to make a tone.
Non-orchestral flutes come in a wide variety of forms. They include vertical flutes like the Irish pennywhistle and the recorder. There is a small "vessel flute" called the ocarina, which may be gourd-shaped or bubble-shaped; one type is played in South Africa. Pan pipes are played in many countries including Uganda and Peru. And some countries, like Tonga in the Pacific, even have nose flutes, blown with the nose.
Until about the 15th century, most flutes were end-blown, like recorders. Side-blown flutes begin to show up in paintings and manuscripts in the 1300s, but their use did not become widespread until the 16th century.
The modern orchestral flute reached its present form in 1847. It is traditionally made of a silver alloy, but some flute players prefer to have part of their flute made of gold or even platinum, for superior tone. Once in a while a flute is still constructed partly of wood, at a player's request. Wooden flutes, still used to play early music, require more breath pressure to get a tone, but their low register is particularly beautiful.