This ActionTab is from the Theory Section where we are looking at registers, octaves and the fact that we have only 12 notes. If the stuff below confuses you, then definitely read the article. It's important stuff.
Here's a simple little tune that most people know. It's quite beginner friendly. We're using the tune to further illustrate the concept of registers / octaves. Here we play the tune 3 times - each time in a different register.
On guitar there are usually 3-4 registers (depending on how many frets you have). Notice that the Star Wars tune sounds exactly the same, except it somehow gets lower each time it is played. That's because we play it first in the high register, then the middle register, then the lowest register.
In music we have only 12 notes. However, these 12 notes repeat through registers. i.e. after the first 12 notes are played (lowest register), then we get into the next register (middle register). After that it's the high register (or 3rd register). I know that we are going down through the registers in this tune, but you get the point.
That's registers for you, now let's take just the very first note of the tune (which is F) and talk a bit about octaves:
Look at the first note of this tune - High F. Play it and listen, then pause the ActionTab. Now look at the next Middle F and do the same thing. Now do it again for the Lowest F.
Notice that each time we get the exact same note - they sound the same, except somehow they are lower. We say that they have the same Pitch (which we label 'F'). The difference is the Frequency at which the string vibrates. That is the factor which determines how high / low the F note sounds.
As musicians we know that these F notes aren't exactly the same. We know they are somehow higher / lower even if the pitch is the same. So, we say that these F notes are an octave apart.
Low F and Middle F are 1 octave apart
Middle F and High F are 1 octave apart
Low F and High F are 2 octaves apart
On guitar an octave is always the distance of 12 frets. Count the distance between Middle F and High F to see (it's all on 1 string).
Mad Scientists should read on...
The difference between octave notes is that the string vibrates faster or slower (depending if you are going higher or lower) always at a 2:1 ratio.
Take the Middle F note. Let's say the string vibrates at 400 Hz (it doesn't - we're just using a nice round figure to illustrate things here). If you play the High F the string vibrates in the same way (giving the same F pitch) BUT the frequency of the vibration is precisely twice as fast (800 Hz). This gives it a higher sound.
Same deal for the Low F - it gives the same pitch but vibrates at only 200 Hz (precisely half that of the middle F). The result is that we have 3 types of F note. The pitch is still 'F'. The only difference (to our ears) is how high / low the F note sounds.
You don't need to know all the science as a guitarist, but some find it interesting. The point is that although we have only 12 notes on any common instrument, each note can be found more than once as we play up or down the fretboard.
Each F note here is said to be an octave apart.
Each time we play the star wars theme it is in a different register (which you can also think of as 'octave ranges').
