Before classical period, Opera was entertainment for only wealthy and royal audiences. And topics of Opera were all about Greek mythology and tragedy. In the classical period, however, Opera became popular entertainment for all kinds of people, and many comedies of Operas came out. Opera has two categories which are opera seria or opera buffa.
Opera seria

• classic topics such as Greek mythology
• retaining barque opera traditions
• appeals to wealthy and royal audiences

Opera buffa

• comic opera
• slap stick and humor
• targeting middle class

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