书籍的右页是书籍右侧的页面, 也称作纸张的正面；左页是书籍的左侧部分的页面, 也称作纸张的反面。它们是装订, 打印和出版业中的术语, 并且可以更广泛地应用在实体文档交流的任何领域.

术语左右页用来描述双面文本, 在手稿学领域有很重要的作用, 每张实体原稿均被编号, 并且每一面都被标上了左页或右页. 原稿的严格版本通常标记文本在原始稿件中的位置, 以类似这样的风格 '42r.' 或 '673vº'.

这些术语贯穿印刷的整个过程, 双面印刷成为印刷书籍的标准, 但双面印刷比更古老的亚洲木板印刷术更有优点, 木板印刷在需要打印纸张的背面摩擦仅能印刷纸张的一面.

The terms recto and verso refer to the text written on the "front" and "back" sides of a leaf of paper in a bound item such as a codex, book, broadsheet, or pamphlet. The terms are shortened from Latin rectō foliō and versō foliō, translating to "on the right side of the page" and "on the turned side of the page", respectively. The page faces themselves are called folium rectum and folium versum in Latin, and the ablative recto, verso already imply that the text on the page (and not the physical page itself) are referred to.