The national flag of the Philippines is a horizontal bicolor flag with equal bands of royal blue and crimson red, with a white, equilateral triangle at the hoist. In the center of the triangle is a golden-yellow sun with eight primary rays, to represent the original eight provinces that rebelled against the Spanish during the 1896 Philippine Revolution. At each vertex of the triangle is a five-pointed, golden-yellow star, each of which representing one of the country's three main island groups—Luzon, Visayas, and Mindanao. The white triangle at the hoist represents liberty, equality, and fraternity. A unique feature of this flag is its usage to indicate a state of war if it is displayed with the red side on top, which is effectively achieved by flipping the flag upside-down.

A national flag is a flag that represents and symbolizes a given nation. It is flown by the government of that nation, but can also be flown by its citizens. A national flag is typically designed with specific meanings for its colours and symbols, which may also be used separately from the flag as a symbol of the nation. The design of a national flag is sometimes altered after the occurrence of important historical events. The burning or destruction of a national flag is a greatly symbolic act.