The "festa" is generally organized as lots of separated parties, usually one for each city. Typical aspects are low-price or free typical foods, live music, prize games and street markets. It takes place in late July or early August.
While the political aspect was preponderant in its first times, and is at times still important, it has developed in a periodic social occasion for both young people (organizing music events and discos) and elderly people (talking about the political adventures of their past and dancing swing).
In some parts of Italy, especially in Tuscany and Emilia-Romagna, each and every small village seems to have their own "festa dell'unità", which is often the biggest social event of the year. In Florence, in the middle of Tuscany, it has developed into a two-week long, tens-of-thousands-people-packed event that has little resemblance to the original political gathering, and is instead one of the biggest attractors for young people in the nearby.
See also: marxism