Racket is a general-purpose, multi-paradigm programming language. The Racket language is a modern dialect of Lisp and a descendant of Scheme. It is designed as a platform for programming language design and implementation. In addition to the core Racket language, Racket is also used to refer to the family of programming languages and set of tools supporting development on and with Racket. Racket is also used for scripting, computer science education, and research.

The Racket platform provides an implementation of the Racket language (including a runtime system, libraries, and compiler supporting several compilation modes: machine code, machine-independent, interpreted, and JIT) along with the DrRacket integrated development environment (IDE) written in Racket. Racket is used by the ProgramByDesign outreach program, which aims to turn computer science into "an indispensable part of the liberal arts curriculum".

The core Racket language is known for its extensive macro system which enables creating embedded and domain-specific languages, language constructs such as classes or modules, and separate dialects of Racket with different semantics.

The platform distribution is free and open-source software distributed under the Apache 2.0 and MIT licenses. Extensions and packages written by the community may be uploaded to Racket's package catalog.

Matthias Felleisen founded PLT Inc. in the mid 1990s, first as a research group, soon after as a project dedicated to producing pedagogic materials for novice programmers (lectures, exercises/projects, software). In January 1995, the group decided to develop a pedagogic programming environment based on Scheme. Matthew Flatt cobbled together MrEd, the original virtual machine for Racket, from libscheme, wxWidgets, and a few other free systems. In the years that followed, a team including Flatt, Robby Findler, Shriram Krishnamurthi, Cormac Flanagan, and many others produced DrScheme, a programming environment for novice Scheme programmers and a research environment for gradual typing. The main development language that DrScheme supported was named PLT Scheme.

In parallel, the team began conducting workshops for high school teachers, training them in program design and functional programming. Field tests with these teachers and their students provided essential clues for directing the development.

Over the following years, PLT added teaching languages, an algebraic stepper, a transparent read–eval–print loop, a constructor-based printer, and many other innovations to DrScheme, producing an application-quality pedagogic program development environment. By 2001, the core team (Felleisen, Findler, Flatt, Krishnamurthi) had also written and published their first textbook, How to Design Programs, based on their teaching philosophy.

The Racket Manifesto details the principles driving the development of Racket, presents the evaluation framework behind the design process, and details opportunities for future improvements.