play music 奏乐 弹琴 玩音乐（music泛指音乐声）
play the music 演奏乐曲（music特指某段音乐）
music本身不可数,第一个,并不是特指什么音乐,所以什么都不用加，
第二个是特指这部电视剧中的音乐,所以需要加the。
拓展延伸：
特指某（些）人或某（些）事物.Give me the book.Did you hear the talk given by Mr Li?How do you like the film.Have you got the letter?
2.指谈话双方都知道的人或事物.Where is the teacher?Open the door.
3.复述上文提过的人或事物.I have a beautiful wallet,but the wallet was stolen yesterday.
4.世界上独一无二的事物等（月亮、地球、天空、宇宙） The sun rises in the east.The earth goes round the sun.the globe,the universe.the atmosphere大气层
5.用在方位名词前 in the south,in the west ,in the north
6.用在序数词或形容词最高级前 The first thing I want to say is to listen carefully in class.He is the tallest one in our class.
7、表示两者间“较……的一个”时用定冠词 The older of the two noblemen took a light.He is the taller of the two boys.
8.用在单数可数可数名词前表示一类人或事物.The horse is a useful animal.
9.定冠词用在形容词前,表示一类人或东西.The rich,the poor ,the wounded ,the deaf
10.冠词可用在党派、阶级、民族名词前 The Chinese people中华民族 The working class 工人阶级 The Communist Party .
11、用在姓氏的复数形式前表示一家人,或这一姓的夫妇二人.The Lius live upstairs.The Johns are watching TV.
12、在乐器前加the the piano the violin
13、在习惯性短语中 in the morning in the afternoon .
14、在人或物后有限定性的后置定语 The man standing by the gate is Li Feng.
15、代替所有格代词,表示人体的一部分 He received a blow on the head 他头上挨了一击.John’s brother took him by the hand.约翰的哥哥牵着他的手
16、在世纪,年代名词前用冠词.In the 1980s或in the 1980’s 20世纪80年代 in the nineteenth century 二十世纪
参考资料：百度百科：the
