Zend引擎是一个开源脚本引擎（一个虚拟机），因作为PHP语言的重要核心而闻名。它原由仍在以色列技术学院的学生 Andi Gutmans 与 Zeev Suraski 所开发。他们之后在以色列特拉维夫的拉马干（Ramat Gan）创立了Zend 技术公司。Zend一名为他们名字Zeev和Andi所组成的新字。

第一版的 Zend 引擎在1999年伴随着PHP第四版问世。它是高度最佳化的后台模块。性能、可靠与延展性是它让PHP更强更大众化的主要原因。

目前版本为Zend引擎 II。Zend引擎依BSD许可证发布。

Zend or Zand is a Zoroastrian technical term for exegetical glosses, paraphrases, commentaries and translations of the Avesta's texts. The term zand is a contraction of the Avestan language word zainti, meaning "interpretation", or "as understood".

Zand glosses and commentaries exist in several languages, including in the Avestan language itself. These Avestan language exegeses sometimes accompany the original text being commented upon, but are more often elsewhere in the canon. An example of exegesis in the Avestan language itself includes Yasna 19-21, which is a set of three Younger Avestan commentaries on the three Gathic Avestan 'high prayers' of Yasna 27. Zand also appear to have once existed in a variety of Middle Iranian languages, but of these Middle Iranian commentaries, the Middle Persian zand is the only to survive fully, and is for this reason regarded as 'the' zand.