A Filofax is a small ring-binder book you carry for addresses, a diary, and things you must do. The pages go on rings, so you can add a page or take one out. It started as a brand name, from “file of facts,” and in Britain in the 1980s it became the fashionable organiser — the thing a busy person flipped open on the train. People still buy the brand, and some speakers use Filofax loosely for any similar book, the way a brand name sometimes stands for a whole kind of thing. It is paper, not an app. Though actually, younger people now keep that same information on a phone. In Taiwan you will more often hear 手帳 or 活頁筆記本; the English brand is less of a street word here, but English books still use it. It is not a fax machine, even though the end looks a bit like fax.

活頁手帳（品牌名；台灣日常較常說手帳、萬用手冊）