Have you ever wondered what's up with musical scales? What are they? Why are they like they are? Musicians seem to think they're cool, but they can't seem to clearly explain why.
Here's an explanation, because I had the same question.
If you look at a keyboard, you're seeing a scale. Plain ol' basic major key C. Whee. The reason it's so hard to understand different keys and scales is because the keyboard is hardwired for that one key, and screw everyone else.
In truth, there's twelve notes in our musical meanderings. The thirteenth note is really just the first note again, except twice as high. Now, from any given note, there is a major chord.
This is your keyboard, starting at C:
(Dashes are those black keys.)
Now, the ways of getting a major chord are simple. The pattern is four, three, five.
Starting from C, count four steps (steps include both black and white keys), then three steps, then five steps. You end up with your fingers on white keys: C, skip the next white key, E, skip the next white key, G, skip two white keys, back to C.
There are other major chords that include C - you can get those by counting three, five, four or five, four, three. Those aren't C chords, however - they're other chords that include C. If you think about it, you'll see you're actually counting four, three, five from some other note.
There's another note that sounds pretty good with C: F. Another white key. That's one of the ones where it's two white keys in a row. Now you know why: because F sounds good with C. At least, that's what I think.
So, what's up with the other break? I dunno. I think it's so that C is easy to find - I don't see any particular reason it's two black keys and then three, rather than three black keys and then two.
ANYHOW, that layout is only really good for C. When you try a D major chord, you get ugly black keys in on it. Fingers want to automatically scale up major chords by simply moving to the right. But they can't, because the keyboard has decided to make your life easier in a single key.
Sure, there's some good reasons for doing scales in this two-two-one-two-two-two-one way. Not least, it gives us a neato pattern that our minds have become used to, allowing us to write subtle nuances into our songs. Like, say, minor keys. Which aren't 2-2-1-2-2-2-1. They're 2-1-2-2-1-2-2... a VERY subtle difference, as you'll see if you count out the A minor scale on a keyboard.
But it does mean that beginners just don't understand scales.
On a guitar, things are different. Instead of having white keys, you have strings and frets. While the frets are marked, they're not bigger or smaller based on some arbitrary scale. So you are essentially left to find your own scales. And your own chords.
See, the guitar is usually tuned 5-5-5-4-5 steps between each string. (Starting from bass.)
As you might remember, the progression for a chord is 4-3-5. Two notes 5 apart and two notes 4 apart always sound good with each other, so any two consecutive guitar strings will sound good strummed simultaneously.
To get a chord, you just have to change the progression between the strings by putting your fingers on frets. By putting a finger on the second fret of the second most bass string, you change the progression to 7-3-5-4-5. By pressing on the third fret of the bassest string, you change the progression to 4-3-5-4-5. By putting your finger on the third fret of the wee little string, the progression becomes 4-3-5-4-8. (8 being 3 + 5: we're skipping a note).
Poof! A chord. In fact, it's almost two octaves of that chord - we could leave off our pinky finger and strum only the first five strings, and we would still have a perfectly viable chord.
If our tuning had been 5-5-5-5-5 instead of 5-5-5-4-5, we would have needed a whole lot more fingers: work it out yourself. Therefore, 5-5-5-4-5. There are other tunings, usually built for making fingerings easier in certain progressions... you can probably see why that's possible and important now.
You can build any number of chords like this (major, minor, whatever). Unlike a piano, you can go up keys simply by sliding your fingers up a fret. (And, you know, fretting all the strings that were open a second ago. Drawback, but still quite clear.)
Now you hopefully know a little bit more about why scales are the way they are, what sacrifices pianos make to be easy to play, and why guitars are cool but a bit unfriendly.