Taffy is a soft, chewy sweet made by boiling sugar with butter and then pulling it — literally stretching the warm mass over and over, which puts air into it, makes it lighter in colour, and gives it that soft chew. It comes in bright colours and lots of flavours, and it is strongly associated with American seaside towns; 'saltwater taffy' from the New Jersey shore is the famous version, sold in little wrapped twists. The important thing for a Taiwanese student is that this is an American word. In British English the same kind of sweet is called toffee, and taffy is not really used. But careful — the two are not exactly the same thing. American toffee is harder and more brittle, closer to what Taiwanese students know as 牛軋糖's harder cousin, while taffy is the soft pull-y one. There is also a completely separate meaning, from a different origin: Taffy with a capital T is an old British nickname for a Welsh person, from the Welsh name Dafydd (David). It is dated and can be offensive, so know it when you read it, but do not use it.