What is the difference between a latte, cappuccino and flat white?

All three are espresso and steamed milk. The differences are the ratio, the texture of the milk, and the volume — and the boundaries vary enough between countries and cafés that no definition is universal.

Cappuccino. Traditionally equal thirds: espresso, steamed milk, and a thick layer of foam on top. Served small, around 150–180ml, in a wide cup. The defining feature is the substantial foam layer — dry, airy, and noticeably separate from the liquid. The Italian original is a breakfast drink, which is the basis of the convention against ordering one after a meal.

Latte (properly caffè latte, meaning milk coffee). Espresso with a much larger volume of steamed milk and only a thin layer of foam, usually 1cm or less. Served large, 240ml or more, often in a glass. It is the mildest of the three, with the coffee most diluted.

Flat white. Developed in Australia or New Zealand in the 1980s — the two countries dispute it — and the defining characteristic is the milk texture rather than the ratio. It uses microfoam: milk steamed to a glossy, paint-like consistency with bubbles so fine they are invisible, integrated fully into the liquid rather than sitting on top.

It is served smaller than a latte, typically 150–165ml, giving a higher coffee-to-milk ratio and a stronger flavour, often with a double shot or ristretto.

Related drinks:

Macchiato — espresso "stained" with a small amount of milk. Very small and strong. Note that the commercial chain version bearing the name is an entirely different, much larger drink.

Cortado — espresso with an equal amount of warm milk, minimal foam.

Americano — espresso with hot water, no milk.

Latte art requires microfoam, which is why it appears on flat whites and lattes rather than traditional cappuccinos.