Best-selling is the adjective that sits in front of a noun: a best-selling novel, a best-selling author, a best-selling album. It means the thing sells in very large numbers, the same idea as best-seller. The hyphen is the usual spelling.

Best-selling is是 sits in front of a noun放在名詞前面 the adjective that的那個形容詞：a best-selling novel、a best-selling author、a best-selling album。It means它的意思是 the thing這樣東西 in very large numbers以非常大的數量 sells賣出，the same idea as和 best-seller 是同一個概念。The hyphen帶連字號 is the usual spelling是通常的拼法。

Same quiet trap as the noun: it talks about sales, not about whether the writing or the product is truly “the best.” Teachers and reviews sometimes blur the two, as if a best-selling thriller must be well written — though actually the charts only count copies sold. Use it before a noun; we do not usually say “this book is best-selling” on its own in careful English (we say it is a best-seller).

as the noun和名詞 Same quiet trap一樣的安靜小陷阱：it它 talks about說的是 sales銷量，not about不是 the writing or the product作品或產品 whether是否 truly “the best”真的「最好」。Teachers and reviews老師和書評 sometimes有時 blur the two把兩者混在一起，as if彷彿 a best-selling thriller一本 best-selling 的驚悚小說 must be well written一定寫得好——though actually不過其實 the charts排行榜 only count只計算 copies sold賣出的本數。Use it把它用 before a noun在名詞前；in careful English在講究的英文裡 we我們 usually不太 on its own單獨 say說 "this book is best-selling"——we say我們會說 it is a best-seller。