Sorry meant to type Bflat 6 in the second to last sentence (in the second answer, the one about the highest notes on flutes)

The answer by Jkat_Knight is really good, and I totally agree with it. Just want to add a couple things. On a regular concert C flute, the lowest note is middle C. On an open-holed flute, the lowest note is the B flat directly below middle C. Apparently extremely experienced can get to C8, which is 4 octaves above middle C ( I can get to C7 - 3 octaves above middle C), but I have never in my life have heard anybody do that, and I find it kind of hard to believe. Most music (at least that I have played) doesn't even go past B flat 7. Hope this helps!

I assume you are talking about the orchestral flute in C Major. The range is from middle C to approximately Bb four octaves higher. The lower register from middle C to the D one octave above is warm, breathy and tends to be soft. The middle register from that D to one octave higher becomes increasingly brighter and stronger on ascent. The high register is brilliant and can sometimes be piercing or shrill.