The trombone is by nature a chromatic instrument and is the only brass instrument whose basic structure has remained the same. The concepts and principle of the movable slide has remained unchanged over the last five hundred years. The name trombone is derived from the Italian tromba (trumpet) and one (large) -which is exactly what the trombone is - a large trumpet. The English name was sackbut.
The first trombone slides probably made possible the extension of the instrument only a short distance, possible enough for for or five semitones. In 1511, Virdung wrote about an instrument with a slide long enough to add five semitones to the natural scale.
By the close of the fifteenth and all during the sixteenth century the trombone remained a very popular instrument, while the trumpet was restricted to use in royal and military functions. During the seventeenth century, trombones were used as a family in a quartet: alto trombone, tenor trombone, bass trombone, and contrabass trombone.
Since the seventeenth century symphonic literature has been written in the alto, tenor, and bass clefs.
Trombones are non transposing instruments with the pitch written exactly as it sounds.
The modern trombone's 22-inch slide can be extended into six lower positions adding six half-steps to the open note. The distance between each slide position is approximately three and a has inches. The distance between each slide position moving from one to seven is approximately 6% more than 3 1/2 inches.
The F valve is usually a rotary valve that adds tubing to the standard tenor trombone in Bb putting it in F. When the F valve is used the instrument's slide has only room for 6 positions.