The Grito de Dolores was the call for the independence of Mexico given by Miguel Hidalgo on September 16, 1810 in the town of Dolores, near Guanajuato. The phrase by which this is known is something of a pun in the Spanish language; "Grito de Dolores" can mean both "The Shout from (the town of) Dolores", and "The Cry of Pain", signifying the pain that the rule of Spain caused Mexico.
Hidalgo rang the church bell to gather his congregation, then called for Mexican independence, the exile or arrest of all Spaniards in Mexico, and ended by calling out, "Mexicanos, viva México!" (Mexicans, long live Mexico!)
Mexico's independence was recognized by the Spanish viceroy in 1821, and since then the President of Mexico traditionally rings Hidalgo's bell (now at the National Palace on the Zócalo in Mexico City) and repeats Hidalgo's words each year at 23h00 on the night of September 15.