Apple events are a message-based interprocess communication system introduced in System 7 for classic Mac OS and still supported in macOS, enabling high-level commands like "open document" or "print file" rather than just basic clicks and keypresses. They are built on a flexible, dynamically-typed data format called AEDesc, which uses OSType codes to define data types, and can be structured into records (AERecord) or lists (AEList) that support recursive nesting and type coercions. Each event carries attributes specifying its target (local or remote, initially via AppleTalk and later TCP/IP in Mac OS 9), its purpose, and parameters, with senders able to receive replies containing error codes or requested data. Crucially, Apple events form the foundation of the AppleEvent Object Model (AEOM) and the Open Scripting Architecture, which powers AppleScript, allowing applications to expose and control each other's internal objects in a standardized way. The official API is available in C/C++ with bindings for Objective-C and Swift through Cocoa, while unofficial bindings exist for languages like Python, Ruby, and Perl.