Flag facts: what the designs actually mean
A flag has to work at a distance, on a pole, in bad weather, so the vocabulary is small and the same shapes recur. What varies is the reasoning behind them, and that is usually more specific than people expect: a particular battle, a particular plant, a particular arrangement of stars on a particular night.
Which country has the only national flag that is not a rectangle?
Nepal
Nepal's flag is two stacked pennants, and its exact geometry is written into the constitution as a construction procedure. Switzerland and the Vatican are square, which is unusual but still rectangular.
Source: Constitution of Nepal, schedule 1
Which country's flag features a building?
Cambodia
Cambodia's flag shows Angkor Wat in white at its centre, the only current national flag depicting a building. Afghanistan's flags have shown a mosque in several past versions.
Source: Cambodian flag law; standard vexillological surveys
Which colour is rarest on national flags?
Purple
Only a couple of national flags use purple, Dominica and Nicaragua among them, and only in small details. Purple dye was historically ruinously expensive, so it never became a common flag colour.
Source: Survey of the 193 UN member state flags
What is unusual about Paraguay's flag compared with every other national flag?
Its two sides carry different emblems
The obverse carries the national coat of arms and the reverse the treasury seal, so the two faces genuinely differ. Almost every other national flag is identical front and back or simply mirrored.
Source: Paraguayan flag law, Ley 5.061/2013
What made Libya's flag from 1977 to 2011 unique in the world?
It was a single plain green rectangle
It was a plain green field with no emblem, charge or second colour: the only national flag of a single solid colour. Libya returned to the earlier red, black and green tricolour in 2011.
Source: Libyan flag history, 1977 and 2011 changes
Which national flag contains the most colours?
South Africa, with six
South Africa's 1994 flag uses black, gold, green, white, red and blue: six, more than any other national flag without a detailed emblem.
Source: South African government flag specification
Which two national flags are so similar they are frequently confused?
Chad and Romania
Both are blue, yellow and red vertical tricolours differing only in the precise shade of blue. Chad objected at the UN when Romania readopted its version in 1989.
Source: UN correspondence, 2004; national flag specifications
Which national flag looks different when flown upside down, and means something else?
The Philippines
Blue is uppermost in peacetime and red on top in wartime, the only national flag with a deliberate wartime configuration. Poland and Indonesia invert into each other's flags by accident.
Source: Philippine Republic Act 8491
How many countries still include the Union Jack on their national flag?
Four
Australia, New Zealand, Fiji and Tuvalu. Several more use it on sub-national or territorial flags, and both New Zealand and Fiji have debated removing it.
Source: National flag specifications
What do the flags of Denmark, Norway, Sweden, Finland and Iceland share?
An off-centre cross
The Nordic cross has its vertical bar shifted towards the hoist. Denmark's Dannebrog is claimed as the oldest continuously used national flag, dating from the thirteenth century.
Source: National flag histories; Danish royal records
Which national flag features a firearm?
Mozambique
Mozambique's flag shows an AK-47 crossed with a hoe over a book. Proposals to remove the rifle have been debated repeatedly and rejected.
Source: Constitution of Mozambique
Which two countries have square national flags?
Switzerland and Vatican City
Both are 1:1. Switzerland's civil ensign at sea is rectangular, because square flags do not behave well on ships.
Which national flag shows a map of the country itself?
Cyprus
Cyprus depicts its own outline in copper above two olive branches. Kosovo is the other current example. The copper colour references the island's ancient copper mines.
Source: Constitution of Cyprus, 1960
Which country claims the oldest continuously used national flag?
Denmark
The Dannebrog is traditionally dated to 1219 and has been in continuous use since at least the fourteenth century, making it the oldest still-flown national flag.
Source: Danish national archives
The crescent on flags such as Turkey's and Pakistan's is most associated with what?
Islam
The crescent was used by Byzantium and later the Ottomans, and became associated with Islam largely through Ottoman use rather than religious doctrine.
Source: Ottoman heraldry; comparative vexillology
The Southern Cross constellation appears on the flags of which countries?
Australia, New Zealand, Brazil, Papua New Guinea and Samoa
It is visible only from southern latitudes, which is why it is a natural symbol for southern-hemisphere states. Brazil's flag shows it as seen from above, mirrored.
Source: National flag specifications