The Form of Tragedy

The traditional tragedy in Aeschylus' time (circa 475 BC) consisted of the following parts:

1. Prologue, which described the situation and set the scene
   
2. Parados, an ode sung by the chorus as it made its entrance

3. Five dramatic scenes, each followed by a Komos, an  
     exchange of laments by the chorus and the protagonist   

4. Exodus, the climax and conclusion

Aristotle - arousing of fear and emotion, purging (catharsis) - the unities: unity of time place and character - Pathos (Greek for instructive suffering) which has come to mean the quality in something that arouses sympathy. 

Often used today to describe something sad but not necessarily tragic. Satyrs, trilogies of tragedies were interrupted by satyr plays (which made fun of characters in the tragedies around them). Hence the word tragedy. Comedy from Komodos which means 'merrymaking,' and 'singer.'