It is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically.
A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent notes in a 12-tone scale (e.g. from C to C ♯). 19-tone equal temperament distinguishes between the chromatic and diatonic semitones; in this tuning, the chromatic semitone is one step of the scale (play 63.2 cents (help·info)), and the diatonic semitone is two (play 126.3 cents (help·info)). Semitones (Half Steps). A semitone (or half step in the USA) is the smallest distance between two different notes. Let's use the piano keyboard to look at some examples of semitones. If two notes are as close as possible on the piano keyboard, the distance between them is a semitone. Find E and F next to each other on the piano keyboard. Definition: A semitone is the smallest musical interval in modern Western music (or, the smallest distance between notes in the chromatic and diatonic scales*). There are two semitones in one whole tone. * A semitone is always a half step; however, it can be called either diatonic or chromatic 1  : Diatonic semitones affect two different note-names; the distance between F and G-flat (pictured) is a diatonic semitone. 2  Chromatic semitones name the same note; the distance between A and A-sharp A semitone is to move from one given note to the very next note immediately above or below. It is an interval equal to a half tone or half-step or minor 2nd in the standard diatonic scale. It is the musical interval between adjacent keys on a keyboard instrument or adjacent frets on a guitar.  Now you understand pitch on a grand orchestral scale. We turn to the smallest intervals in western music the tones and semitones. The letters of the alphabet are separated by tones and semitones. E to F is a semitone. Twice a semitone is a tone. F to G is a tone. The alphabet is not equidistant.  In music theory, a distinction is made between a diatonic semitone, or minor second (an interval encompassing two staff positions, e.g. from C to D ♭) and a chromatic semitone or augmented unison (an interval between two notes at the same staff position, e.g. from C to C ♯). 19-tone equal temperament distinguishes between the chromatic and diatonic semitones; in this tuning, the chromatic semitone is one step of the scale (play 63.2 cents (help·info)), and the diatonic semitone is two (play 126.3 cents (help·info)). Semitone. A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent notes in a 12-tone scale.  A cent is a hundredth of a semitone – it is the interval we would get if we partitioned the octave into 1,200 equal musical intervals, and therefore correspond to a ratio of the 1,200th root of two between the frequencies of two notes. The musical interval between two adjacent notes in a partition of the octave into twelve (not necessarily equal) intervals is called a semitone; other names for it are a half step and a halftone. The smallest interval in use in the Western musical tradition is the semitone (also called half step). It is the interval between any note and its nearest neighbour on the keyboard. Two semitones together form one tone (or whole tone or whole step). Audio 1 From C to C# (or Db) is a semitone. From C# to D is also a semitone. Therefore from C to D is 2 semitones or 1 whole tone. (Down-Up-Top-Links) JT 1.2 - The Chromatic scale There are a total of twelve notes within an octave, represented by the 12 keys on the keyboard. All notes are spaced at semitone intervals. 8-note Diminished scale (tone-semitone-tone-semitone -) This scale starts with a tone between the tonic and 2nd note, then a semitone between the 2nd and 3rd notes, again a tone between the 3rd and 4th note, and so on. Audio 5 In Jazz this scale is used for improvisation over diminished chords (see Lesson 15). In the equal temperament, when the twelve intervals are equal, two notes are a semitone apart if the ratio between their frequencies is the 12th root of 2, or about 1.05946. The musical interval between two adjacent notes in a partition of the octave into twelve (not necessarily equal) intervals is called a semitone; other names for it are a half step and a halftone.
https://en.wikipedia.org/wiki/Semitone http://www.mymusictheory.com/for-students/grade-1/grade-1-course/111-10-tones-a-semitones http://piano.about.com/od/musicaltermsa1/g/GL_semitone.htm http://www.bellandcomusic.com/tones-and-semitones.html http://musicarrangers.com/star-theory/p04.htm https://en.wikipedia.org/wiki/Semitone http://www.definitions.net/definition/semitone http://www.yuvalnov.org/temperament/tone.html http://jazclass.aust.com/lessons/jt/jt01.htm http://www.yuvalnov.org/temperament/tone.html
what is a semitone