Philadelphia is the cornucopia of festivals. There is something for everyone all year round. As far as the most popular festivals, it depends on who you ask.
If you are a food lover there are three festivals that are totally worth checking out. Festival of Forgotten Food, the Italian Market Festival and East Passyunk's famous Flavors of the Avenue. all of these offer tastes of some of the best food Philly has to offer. It is also a geat time for family and friends to enjoy an outing surrounded by food.
If you are an art lover there are some great choices. The International Festival of art is a Month Long extravaganza that celebrates all angles of art via dance, music and visual. Learn about the history of music through lectures and performances. It is definitely worth it. The Women & Music Festival is also a must visit. This festival isn't as celebrated as others in the city but it offers much information about women in the musical arts.
If you are looking for a bit of culture there are two festivals that are a must do. The Odunde Festival celebrates African culture via food, art, and entertainment. Vendors offer a variety of cuisines that send your taste buds right to the Ivory Coast. Another is the Filadelfia Latin american Film Festival. This event focuses on Latin Films, including Latin directors, actors and actresses. It breathe the Latin-American culture and offer a great day of cinema.
A few other festivals that don't really fall into a particular category but are truly worthy of participation are: the South Street Spring Festival, the Philadelphia Honey Festival, the Rittenhouse Row Spring Festival, the Philadelphia Book Festival and the Strawberry Festival. all are a great time for family or friends.