The generally accepted meaning of the word interval is of course known to all. As indicated by the Latin "ancestor" of the word - intervallum is the gap distance. We often meet with them in everyday life. For example, at the bus stop written: "the Interval during peak hours five minutes."
In music, an interval is the same length. But not in time, and in the height of the sounds. Go to the piano or the piano, which I probably should have in school, the House of pioneers or club. Or look at these virtual keyboard.
Press. Sounds kind of note. Repeat it. In music it is considered an interval is the smallest possible. It's called prima (Latin prima - first). If you click two adjacent white keys, you get the next largest interval - seconds (secunda - second).
Look carefully at the keyboard: between the white keys in a certain order settled black. In some places the two white are close by, and in some places black separates two white from each other. If you down the white keys black was not, the distance between the sounding notes - semitone. This second is called small. If a black key between them, the distance between the two sounds twice as much - two semitone or a whole tone. This second is called great.
If you press through a single white (then between them will be one or two black), it will sound beautiful, harmonious interval of a third (tertia third). Depending on the distance in half, or two tone (now you can calculate) the third will be small or large. It is the third sounds are often located in the chords.
These intervals are called Quarta (fourth), QUINTA (fifth), the sixth (the sixth), the seventh (seventh), octave (eighth).
Octave is a very important interval. There are octave frequency sounds. Eighth repeats the first, but sounds an octave higher. Therefore, the name sounds just seven - do, re, mi, FA. Sol. La, si,.. and then again to re... Lower the sound of each interval is called the base, the top - top.
As you already noticed, the intervals differ from one another not only for its width (as determined by the title), but also the quality (that is what he is). Some intervals are large or small, others - net, decreased and increased. However, increased can be all intervals without exception, and reduced all but the prima, which decrease nowhere.
There are intervals and more octaves. They are called compound, for example, Nona (second through octave), Decima (through third octave) and other
The sounds that make up the interval can be taken sequentially, one after the other. Then a melodic interval. If you remove both sounds at the same time, you get a harmonic interval.