References to the guitar more or less in its modern form date back to the 14th century. In its infancy it had four courses of double strings and a rounded body like a gourd or a pumpkin. Its mother would not recognize it today!
Around the sixteenth century the guitar was a popular musical instrument amongst the middle and lower classes of Europe, and as it increased in popularity it began to undergo a change of shape. Luthiers began making instruments with single strings instead of courses and experimented with its form until, by the 19th century, the body of the guitar was made wider, and flattened out. In the twentieth century the wooden tuning pegs which adjusted the tension of the strings were replaced by metal machine heads. Now we have the shape that the modern electric guitar is based on.