The 5th of May commemorates the Battle of Puebla in 1862 when Mexican troops finally defeated the French Army. Oddly less well celebrated in Mexico (it is not an Independence day for Mexico though commonly mistaken for one), America widely supports this festival.
To get the best exposure to the festivities, it is recommended that you visit Denver in the United States. Denver hosts the largest celebration for Cinco de Mayo, drawing crowds of nearly half a million people.
Lavish parades and entertainment, music, dancing, crafts and food fairs all combine to make a fantastic fiesta. And of course, no one forgets the piñata!