The History of Portugal can be separated into seven broad times. The first begins in the Paleolithic time and extends to the formation of Portugal as an independent monarchy. During this time, Lusitania, that portion of the western Iberian Peninsula known today as Portugal, experienced many waves of conquest and settlement by Iberos, Phoenicians, Greeks, Romans, Swabians, Visigoths, and Muslims. Of these successive waves of people, the Romans left the greatest imprint on present Portuguese society.

The sixth, the time of constitutional monarchy, begins with the liberal revolution of 1820, which accomplished in Portugal for the first time a written constitution. This time includes a civil war in which constitutionalists triumphed over absolutists, the winning of freedom by Brazil, and the exploration of Portugal's African possessions. It ends with the collapse of rotativismo in the early twentieth century.

The final time begins in 1910 with the downfall of the monarchy and the establishment of the First Republic. This time includes the corporative republic of António de Oliveira Salazar; the collapse of that regime on April 25, 1974; and the establishment of Portugal's present democratic regime, the Second Republic.