What does it mean to play a song in a certain key?
Basically it’s the “root” pitch. Western music follows a basic pattern of pitches called keys, labelled A through G with various halfway points called sharps or flats. Most tunes, once it’s picked a key, will stick to it. Wandering away from the key tends to sound dischordant, unless it is a key change which is where the whole tune rises or lowers in pitch.
Music isn’t so much about an absolute key (or pitch), but about the differences between the pitches of each note in the tune. You can therefore play any tune at any key and it would still be recognisable as that tune. Singers, therefore, often change the key of a song to best match their vocal range. Other musicians may prefer one key to another simply because it is easier to play on their particular instrument. In order that the other musicians match this, they are informed that they are to play in the key of …whatever. Ideally this is what they will have practiced in, or what the sheet music is printed in. But a professional musician should be able to transpose keys automatically in their head.
All they need to know at the start is what key it’s in.
Take a look at a piano keyboard. Go on. Take a good, long, steamy look at it.
Notice anything about the black keys? That’s right. Not every pair of white keys has a black key between them. You’ll see three black keys, then two white keys right next to each other, then two more black keys, then another two white keys right next to each other, and then the pattern repeats.
Now, look at one of the two-black-key groups. The white key to the immediate left of the first black key is called “C”. The white key to the left of C is called “B”. Notice that there is no black key between B and C. The white key to the right of C is called “D”. Notice that there is a black key between C and D. The next white key to the right of D is called “E” (there’s a black key between D and E), the white key to the right of E is called “F” (no black key between E and F), then G, then A, then B, and then we’re back to C again.
Okay, now. Play the white keys left-to-right, starting with C. Go on, I’m waiting. Play:
C-D-E-F-G-A-B-C
… in that order. Notice anything? The sound frequency difference (called the “pitch interval”) between E and F is smaller than the difference between C and D, or the difference between D and E. Likewise, the pitch interval between B and C is smaller than the interval between F and G, G and A, or A and B.
The “big” intervals – C-D, D-E, F-G, G-A, and A-B – are called whole steps. They always have a black key sandwiched in between them. The “small” intervals – E-F and B-C – are called half steps. They never have a black key between them. The pattern of whole-steps and half-steps in the sequence CDEFGABC is called a major scale. It’s the position of the two half-steps among that sea of 5 whole-steps that gives a major scale its particular “flavor.” If you were to instead play the
following:
A-B-C-D-E-F-G-A
… it wouldn’t sound like a major scale. Even in you closed your eyes and had somebody else play that sequence of notes, and you didn’t know that the pitch he started off on was in fact “A” and not “C”, the half-steps would be in the wrong place. It would sound like a different kind of scale altogether, called a minor scale.
But now, watch the magic.
Suppose you started using those sneaky little black keys to play some of the notes. Suppose instead of playing C, F, and G, you played “sharped” versions of C, F, and G. That is, you played the black keys immediately to the right of C, F, and G, rather than the white keys themselves. I.e., what if instead of playing:
A-B-C-D-E-F-G-A
… you played:
A-B-C#-D-E-F#-G#-A
… where “C#” means “C-sharp,” i.e. “use the black key immediately to the right of C”. If you did this, you would discover that the pattern of whole-steps and half-steps exactly matches the pattern you hear when you play:
C-D-E-F-G-A-B-C
… In other words, “A B C# D E F# G# A” is a major scale, just like “C D E F G A B C” is. The only difference is it doesn’t start on C, it starts on A.
Okay, now the payoff of this whole discussion:
The note that a major scale starts on is called the KEY of that scale. C-D-E-F-G-A-B-C is said to be in the key of C major. A-B-C#-D-E-F#-G#-A is said to be in the key of A major.
Thus, if the music doesn’t have any sharps (or, for that matter, “flats”) in it, it’s in C major. If it has C#, F#, and G# all over the place in it, it’s in A major. There are similar rules for other keys: If there’s a lot of F#'s in it but no C#'s or G#'s, it’s probably in the key of G major, because G-A-B-C-D-E-F#-G also constitutes a major scale.
End of lesson 1.
WOW!
Why weren’t you MY music teacher?
What tracer said.
[sub]I’m so ashamed of myself that I automatically assumed that the thread title referred to your preference for buxom cheerleaders…[/sub]
YWalker wrote, in teeny tiny type:
In that case, wouldn’t the title have been “Gimmie a double-D”? 
Nah. As the saying goes, more than a handful is a waste.
I wanna echo the “great job tracer” sentiments.
Oh and…
I wanna get totally wasted!
Hey, I even pictured trampolines…
Have you never heard of Irving Cohen, who wrote so many songs for the great Sophie Tucker, Last of the Red-Hot Mamas, in a little thing we called Vaudeville??
Even cooler: if you improvise a melody on just the white keys, but force yourself to think of D as the root, you’ll get a totally different feel. Try vamping on Dm and Em and base your melody on the white keys–you’re using a Dorian scale which is all the white keys from D to D. It’s basically minorish in feel, but slightly different from the true related minor which is Am
The melody to “Scarborough Fair” is in the Dorian mode.
I mean, listen to the note that’s played on the “ry” of “Parsey, Sage, Rosemary and Thyme”. It’s the 6th scale degree of a major scale! If you were playing this tune in A minor, you’d have to play an F# instead of a natural F.