The flag of Portugal is the national flag of the Portuguese Republic. It is a rectangular bicolour with a field divided into green on the hoist, and red on the fly. The lesser version of the national coat of arms of Portugal is centered over the colour boundary at equal distance from the upper and lower edges. Its presentation was done on 1 December 1910, after the downfall of the constitutional monarchy on 5 October 1910. However, it was only on 30 June 1911, that the official decree approving this flag as the official flag was published. This new national flag for the First Portuguese Republic, was selected by a special commission whose members included Columbano Bordalo Pinheiro, João Chagas and Abel Botelho. The conjugation of the new field color, especially the use of green, was not traditional in the Portuguese national flag's composition and represented a radical republican-inspired change that broke the bond with the former monarchical flag. Since a failed republican insurrection on 31 January 1891, red and green had been established as the colours of the Portuguese Republican Party and its associated movements, whose political prominence kept growing until it reached a culmination period following the Republican revolution of 5 October 1910. In the ensuing decades, these colours were popularly propagandised as representing the hope of the nation (green) and the blood of those who died defending it (red), to endow them with a more patriotic and dignified, therefore less political, sentiment.

The coat of arms of Portugal is the main heraldic insignia of Portugal. The present model was officially adopted on 30 June 1911, along with the present model of the Flag of Portugal. It is based on the coat of arms used by the Kingdom of Portugal since the Middle Ages. The coat of arms of Portugal is popularly referred as the Quinas.