It is a landmark instrument that has become the epitome of over a half a century of music. The guitar is the cornerstone of much of modern music because of how it can be used to support many different kinds of music, and because of much power and versatility you get out of it compared to the effort that it takes to learn it.
The guitar is one of the most flexible instruments in the world of music. It can play chords and support with harmony like a harp or a piano. It can be purely percussive like a drum. Or, the guitar can play melody like a saxophone. It can do a combination of these things. A guitar can also play classical music, or rock, or jazz or any number of genres in between. This makes the guitar an awesome instrument to choose to learn, because you can use it to fulfill many different types of goals that you have in music.