This document discusses AppleScript and how it works under the hood. It notes that AppleScript is actually two parts: the language itself and the Open Scripting Architecture (OSA) which is the underlying plumbing. OSA allows apps to send Apple Events to each other to communicate and share data. While AppleScript code looks English-like, it is actually querying apps and returning results, similar to how SQL queries databases. Alternative libraries like rb-appscript provide a more consistent interface to access OSA without AppleScript's complexity. The document demonstrates how to use rb-appscript to modify phone numbers in the macOS Address Book application.