Classical music is essentially a set of specific genres of music written between 1600 and the present time for a set of what we call "classical" instruments. These include: piano, harpsichord, clavichord, organ, violin, viola, 'cello, bass, percussion, trumpet, trombone, french horn, tuba, flute, oboe, clarinet, bassoon, harp, and the human voice. This list is by no means all-inclusive.
Classical Music is all about sharing the composer's emotion with his audience. The success which a composer has in communicating his emotions to his audience, determines the quality of his music. Some people feel that classical music is only about being profound, and extremely deep - and that it is only for people who understand it. This is most certainly not the case. Everybody is capable of enjoying Classical Music with or without a musical background. To quote Benjamin Zander "Everybody loves classical music, but some people have not discovered that they do."
The Boston Symphony Orchestra is, in my opinion, the greatest symphony orchestra in the world. Housed in Boston's magnificient Symphony Hall (one of the premier concert halls of the world) they perform a new concert almost every week from September to May. During the Summer, they travel to the Tanglewood Music Center in western Massachusetts, where they perform multiple new concerts a week, for six weeks.