There is no clear inventor of the viola, but it is documented in images and text around the same time as the violin came to be in the early 1500s. The viola and violin are similar in many ways, but the viola is larger and has a deeper sound.
The term "viola" was used at the time to refer to any Western instrument strung in a classical manner. The viola is sometimes referred to as the alto-tenor violin due to the low tones that it produces. Music that is written for the viola uses the alto clef which is rarely ever seen in music for other instruments. In the early part of the 20th century many composers began to write for the viola due to the number of soloist who were specializing in the instrument.