An octave is an interval of an 8th, such as C to C, or A to A. It is a frequency doubling or halving of a tone (twice as fast or slow).In Western music, scales are typically heptatonic (7 tones). Therefore, the completion of a scale, whether Major or minor or other, is the 8th, which is the same letter name, or tone, as the first. (Oct- means eight). Within an octave are 13 tones (13th completing), and 12 half steps.
In cultures using Pentatonic scales (5 tone scales) as their primary melodic & harmonic tone material, the 'octave' could be called a 6th, rather than an 8th. In 12 tone music (dodecaphonic), the 'octave' could be called a 13th.
What follows is all 7 of the octave shapes with 1 double octave (8 total, unless you can reach some more double octaves - go easy & never strain your hands).
Some are more difficult to mute & move than others. Here is some TAB for showing which octave shapes we consider more & less useful (depending on how you use them):
In the video, I used a 3rd finger on the 6th string, 13th fret, rather than the pinky. Use the fingering below the TAB. FH = Fretting Hand.Guitar octaves with scales filling them in