A quarto is a size of paper, and a size of book made from that paper. You take one large sheet, fold it in half, then fold it in half again. That gives you four leaves — which is why the word points at “fourth.” Print on both sides and those four leaves become eight pages.

A quarto是 a size of paper一種紙的尺寸, and也是 a size of book made from that paper用這種紙做出來的書的尺寸。You你 take one large sheet拿一大張紙, fold it in half對摺一次, then再 fold it in half again對摺一次。That這樣 gives you four leaves就得到四張葉子（四折頁） — which is why the word points at "fourth."這也是為什麼這個字指向「第四」。Print on both sides兩面都印的話, those four leaves become eight pages這四張葉子就變成八頁。

Printers, librarians, and people who study old books still say a book is “in quarto,” or call it a quarto. It is not a word for the A4 or 16K paper on your desk; it belongs to an older folding system. A folio (folded only once) is larger; an octavo (folded three times) is smaller.

Printers印刷業者、librarians圖書館員, and people who study old books還有研究古書的人 still say a book is "in quarto,"還是會說一本書是「in quarto」, or call it a quarto或直接叫它quarto。It它 is not a word for the A4 or 16K paper on your desk不是用來指你桌上的A4或16K紙; it belongs to an older folding system它屬於一套比較舊的折疊系統。A folio (folded only once)folio（只對摺一次）is larger尺寸比較大; an octavo (folded three times)octavo（折三次）is smaller尺寸比較小。

You will meet quarto in libraries, auctions, and notes on early printed plays — cheap single plays in Shakespeare’s time often came out as quartos, smaller and less grand than a collected folio. Everyday people just say “a small old book.” The word feels specialist, not chatty.

You will碰到quarto出現 in libraries, auctions, and notes on early printed plays在圖書館、拍賣，還有早期印刷劇本的說明裡 — cheap single plays in Shakespeare's time莎士比亞時代那些便宜的單本劇本 often came out as quartos常常就是以quarto的形式出版, smaller and less grand than a collected folio比一整本合集的folio小、也沒那麼氣派。Everyday people一般人 just say "a small old book."就直接說「一本小小的舊書」。The word這個字 feels specialist, not chatty讓人感覺很專業，不是聊天用語。