An IOU is a short written note that says you owe someone money. You often just write those three letters, the amount, and your name on a scrap of paper — friends and family use it when they borrow a little cash and do not want a bank or a lawyer.

An IOU is IOU是 a short written note一張簡短的字條 that says you owe someone money上面寫著你欠某人錢。on a scrap of paper在一張隨手的紙上，you often just write你常常就只是寫下 those three letters這三個字母、the amount金額、and your name和你的名字——friends and family use it朋友和家人會用它 when they borrow a little cash當他們借一點點現金、and do not want a bank or a lawyer又不想找銀行或律師的時候。

It feels informal.

It feels informal這感覺很隨性、不正式。

The letters are simply “I owe you” said out loud; people have written them this way since at least 1618.

The letters are simply "I owe you" said out loud這幾個字母就是把『我欠你』唸出來的音；people have written them this way since at least 1618人們至少從1618年就開始這樣寫了。

Though actually, people also say “I’ll give you an IOU” as a light promise even when nothing is written down.

Though actually不過其實，people also say人們也會說 "I'll give you an IOU"『我欠你一張IOU』 as a light promise當作一個輕鬆的承諾，even when nothing is written down就算根本沒寫下來也一樣。

An IOU is only as strong as the trust between the two people: a shop will not take it like a card, and it is not money in your hand.

An IOU is only as strong as the trust between the two peopleIOU有多可靠，就看兩個人之間的信任有多深：a shop will not take it like a card店家不會像收卡一樣收它，and it is not money in your hand它也不是你手上的現金。