This document provides an overview of SAS macros, including: 1) The purpose of the SAS macro facility is to allow for dynamic and self-modifying SAS programs through the use of special programs called macros that can generate tailored SAS code. 2) There are two types of macro variables - automatic variables created by SAS and user-defined variables created within the SAS program. 3) Macro variables can be created using %LET, CALL SYMPUT, and the INTO clause and can be either global or local in scope.