Many people that play a guitar knows there instrument very well, but do they know it's history?  There is not any concrete facts but guitars or similar instruments have been around for about five thousand years.  In 1400BC the Hittites played a four string guitar like instrument.  It had soft curved sides somewhat similar to our current guitars.  Approximately around this time the Greeks produced a similar instrument which was modified by the Romans and they called it a cithara.  By 1200AD there were two types of guitars, one was the Moorish guitar and had a wide fingerboard, rounded back, and several sound holes.  The other type was the Latin guitar and it looked more like today's guitars with a narrower neck and just one sound hole.  A new guitar called the vihuela came on the scene in the late 1400s and was a large instrument with double the strings of the Latin and Moorish guitars, a longer neck and ten or eleven frets.  Until the late 1600s the vihuela and another instrument called the lute were more popular than the guitar.  The popularity of the lute declined due to the fact that it had too many strings and was too hard to play and tune.  The vihuela was replaced by four and five course guitars.  Four course guitars had seven strings, a single high string and three pairs of other strings, while five course guitars had nine strings, a single high string and four pairs of other strings.  Many people feel that adding the fifth course gave the guitar greater flexibility.  This is the reason why the guitar became popular.  By the 1800s some guitars used fan struts under the soundboard and had six strings.  During this time the neck also changed, the fingerboard, and the tuning pegs also changed.  Guitars like these are most closely resembles the early classical guitars.  During the late 1800s Antonio Torres Jurado changed the guitar by refining the strutting.  This allowed for as many as seven struts to be spread out like a fan under the soundboard.  The size of the body and the width of the neck were also greatly increased.  Due to these changes the guitar had greater bass response and volume.  Today's guitars are practically the same as the ones made by Jurado.