The biscuit was a preservation technology

'Biscuit' comes from words meaning twice-cooked, and the Italian 'biscotti' says the same thing in the same way. The second cooking is not baking — the thing is already baked — it is drying, and the point of the drying is that a food with very little water in it does not spoil.

That is why ships' biscuit, army biscuit and travellers' biscuit exist in almost every tradition with a coastline or an army. They are storage.

Modern biscotti are a direct survival of the original method rather than a stylistic reference to it: bake the log, slice it, dry the slices. The result is hard because it is supposed to be, which is also why they are made to be dipped.

Once sugar and fat were cheap and food preservation was solved by other means, the biscuit kept its low moisture and lost its reason for it. What arrived instead was texture as a design goal — short, snapping, chewy, crisp — with fat and sugar as the levers.

That is the family this site describes: low final moisture and a high proportion of fat and sugar to flour, where spread during baking is the primary design variable. The dryness is inherited; the purpose is new.

British 'biscuit' and American 'cookie' both descend from this history and now name different things, and the words crossed in a way that is genuinely confusing rather than merely different.

In British usage a biscuit is hard, sweet and low-moisture and a cookie is a specific soft American style. In American usage a cookie covers the whole family and a biscuit is a soft, savoury, chemically leavened quick bread — closer to a British scone than to anything sweet.

BakeHQ records both terms with their notes rather than choosing one, and covers the terminology in more detail in its own record.