Knowing the difference between these two words can make you a stronger writer – at least in the grammar arena.

Armor is a protective covering worn by knights and other warriors. It also can refer to tanks in modern warfare. This is the preferred spelling in American English.

Armour means exactly the same things but is standard in British English. The split in spellings between the two sides of the Atlantic dates to the 1800s.

One easy way to remember which spelling is which is that in the United Kingdom – which begins with a U – a u appears in the word.