The Universal Product Code symbol, also known as the 'bar code', is printed on products for sale and contains information that a computer can read.

通用产品代码符号，亦称“条形码”，印在出售的商品上，其中含有计算机能识别的信息。

《牛津词典》

If a number, it is sent to a remote computer which responds with an instruction that tells the phone to perform an action associated with that particular bar code.

如果是一个数字，那么就会把它发给远端的电脑，电脑就会反馈回一条指令，让手机去完成一个和该条形码相关的操作。

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To check out a book, students swipe a bar code placed inside the book at a computer station, which then asks for them to press their thumb on a fingerprint scanner.

学生借一本书，必须先由电脑扫描书本内页条形码，然后再由他在指纹扫描仪上按压自己指纹。

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Both YottaMark and FoodLogiq offer systems that let shoppers type a text code into a mobile phone or home computer, or scan a bar-code using a phone's built-in camera, to find out when the tomatoes on the shelf were picked and which field they came from.

ECONOMIST: Tech.view