Flutes are part of the Woodwind section of the orchestra. Here is a panshot along the three types of flute - C flute (held), alto and bass:

For comparison, here is the opening of Debussy's Prélude à l'après-midi d'un faune played on bass, alto and C flute in succession:

Ken Smith plays part of Mendelssohn's Scherzo on the bass flute, demonstrating the difficulties of breathing and articulation on the instrument:


Piccolo

The piccolo sounds an octave higher than written:
Unique features:
Construction: v
Registers:

Flute

The flute (or C flute) does not transpose. It has three joints:
Foot joint
Body and Head joint.
How the sound is produced:
How tuning is adjusted:
The first and second octave:
The third octave:

Alto Flute

The alto flute is pitched in G and sounds a perfect fourth lower than written.
Construction:
Sound production:
The low register:
The high register:

Bass Flute

The bass flute sounds an octave lower than written.
Construction:
Dynamic range:
The low register:
The mid and high registers:
Playing the bass flute: