Why is Romeo exiled?

Romeo is exiled from Verona for killing Tybalt in a street fight. Tybalt was a member of the Capulet family, who are the sworn enemies of the Montagues, Romeo's family. The Prince of Verona decrees that Romeo must be exiled as punishment for his crime, and if he is found in Verona after the time limit, he will be executed. Romeo is devastated by the news, as he knows that this will mean he will be separated from his beloved Juliet, who is a Capulet.