A festival might be an all-day series of music performances or a weekend of short plays or films. Any program made up of many different acts, especially lasting an entire day or several days, can be called a festival.
Another meaning of the word festival is "big party," again most often a celebration that lasts for a long period of time. Some festivals are religious, and others are seasonal or cultural, like a city's Italian Heritage Festival. Some famous festivals include the Fringe Festival in Scotland, Carnivale in Brazil, Oktoberfest in Germany and Burning Man in the United States. You could travel the world as a festival hopper.