The clarinet was invented about 1690 in Germany by Johan and Jacob Denner. They modified an earlier musical instrument known as the "chalumeau" by increasing the range of instrument by more then two octaves and improved instrument's mouthpiece and the bell.
In the middle of the 19th century Klose adjusted the Boehm flute key system to the instrument. There are many types of clarinets, including the very rare BBB octo-contrabass to the A piccolo clarinet. The most common is soprano clarinet with a range of almost four octaves.
The very first composer who utilized the clarinet in a symphony was Wolfgang Amadeus Mozart.