The flag of Colombia was adopted on November 26, 1861. It is a horizontal tricolour of yellow, blue and red.

The horizontal stripes (from top to bottom) of yellow, blue and red tricolour have a ratio of 2:1:1. It, together with that of Ecuador, also derived from the flag of Gran Colombia is different from most other tricolour flags, either vertical or horizontal, in having stripes which are not equal in size. (Venezuela, whose flag is also derived from the same source, opted for a more conventional tricolour with equal strips). Wikipedia