Feria is a spring fair that occurs every year in April (except this year when it was in May- HA!). Most of the students in Sevilla get the entire week off of school for the celebration which occurs on the opposite side of the river.
It is a festival filled with horses, lights, drinking, flamenco dresses, and traditional Sevillana flair. The majority of the women wear flamenco dresses while the men wear suits. There are thousands of casetas (drinking tents), set up around the fair grounds. The majority of the casetas are private, meaning that you have to know the family who is paying for / running the caseta to get in. However, once you get into the caseta, there is endless rebujito (sherry and sprite), which is the traditional drink of Feria.
As I only got to see the Feria for one day before heading out on another week-long trip, I did not invest in a flamenco dress. I guess it gives me an excuse to come back for the full week in the future!