The word "octave" comes from the Latin octo, which means "eight." This term is used in both music and literature. In the first case, this is an interval consisting of a certain number of tones and semitones, in the second, a special form of a poetic stanza.
Eight steps
Take a look at the piano keyboard. Even those who have never played the piano have probably noticed that the keyboard is made up of groups of keys arranged in a specific order. The black keys are located in groups of two and three, the white ones are between them, and there are no black keys between some of the white keys.
Press any white key. For example, let it be to the left of a group of two blacks. Find another of the same group, closest to the left or to the right, and in it - the key with the same position. This is the octave. Count the number of white keys, starting from the one you pressed first to the last one. There will be exactly eight of them. In this case, this is the usual scale: "do", "re", "mi", "fa", "sol", "la", "si", "do".
Each octave has its own name. The one in the middle of the piano keyboard is called the first, to the left of it is the small one, to the right is the second.
Tone and semitone
Each sound has a specific pitch. There is one semitone difference between the sounds that can be obtained by pressing adjacent keys (regardless of whether they are white or black). Between the “C” key (the one to the left of the group of two black keys) and the closest black (“C-sharp”) there is a semitone. Accordingly, there will be two semitones before the next white, that is, tone.
Count how many tones are in an octave. From "to" to "mi" - 2 tones, from "mi" to "fa" - semitone, from "fa" to "si" - 3 tones, from "si" to "do" - semitone. It turns out that in an octave there are 5 tones and 2 semitones, that is, a total of 6 tones. The order of the arrangement of tones and semitones determines one or another musical system. For example, any major scale is constructed like this: 2 tones, semitone, 3 tones, semitone. Natural minor is 1 tone, semitone, 2 tones, semitone, 2 tones. Knowing these sequences, you can build any natural scale.
The order of tones and semitones is very important if you are going to learn to play instruments where the position of each sound is not fixed as rigidly as on the piano.
Poetic octaves
In the literature, an octave is called a stanza consisting of eight lines. However, the number is not everything, because a small poem can also be composed of eight lines, written in two quatrains without an interval between them. The octave presupposes a special organization of the stanza. The most striking example is the famous Pushkin octaves, which were used to write the novel in verse "Eugene Onegin". Pay attention to the rhyme scheme. In the first part of the stanza, it is cross, in the second - adjacent, and the author adheres to this order throughout the work.