#lang quadwriter/markdown


A _macro_ is a syntactic form with an associated _transformer_ that
_expands_ the original form into existing forms. To put it another way,
a macro is an extension to the Racket compiler. Most of the syntactic
forms of `racket/base` and `racket` are actually macros that expand into
a small set of core constructs.

Like many languages, Racket provides pattern-based macros that make
simple transformations easy to implement and reliable to use. Racket
also supports arbitrary macro transformers that are implemented in
Racket—or in a macro-extended variant of Racket.

This chapter provides an introduction to Racket macros, but see [_Fear
of Macros_](http://www.greghendershott.com/fear-of-macros/) for an
introduction from a different perspective.