The invention of the guitar cannot be attributed to a single individual, as it evolved over centuries from earlier stringed instruments. However, key figures contributed significantly to the development of the modern guitar:

• The earliest guitars appeared in Spain around the 15th century, evolving from instruments like the Gittern and the Vihuela, which were predecessors to the modern acoustic guitar

• Antonio Torres Jurado, a Spanish luthier in the mid-19th century, is credited with developing the prototype of the modern classical guitar by standardizing its size, shape, and design, including the deeper body and tuning gears that allowed finer tuning

• Christian Frederick Martin, a German immigrant to the United States, is recognized for inventing the first steel-string acoustic guitar in the early 19th century. He designed the guitar's internal structure to withstand the tension of steel strings, enabling banjo players to transition comfortably to the guitar. His work laid the foundation for the modern acoustic guitar widely used today

• The electric guitar was invented much later, with Adolph Rickenbacker credited for creating the first electric guitar in 1931, known as the "Frying Pan." This innovation used pickups and amplifiers to make the guitar audible in larger venues and revolutionized guitar music

In summary, while the guitar's origins trace back to early stringed instruments in Spain, Antonio Torres Jurado shaped the classical guitar form, Christian Frederick Martin innovated the steel-string acoustic guitar, and Adolph Rickenbacker invented the electric guitar. Each played a pivotal role in the guitar's evolution into the instrument known today.