Squeak is an implementation of the Smalltalk programming environment that is designed to allow code to be run on any major operating system , including Windows 95/98/NT, Windows CE , and UNIX . Squeak includes a Smalltalk-80 compiler and a caching just-in-time compiler (JIT) compiler and a large class library. The environment supports real-time sound and music synthesis, Musical Instrument Digital Interface ( MIDI ) performance and scheduling, text-to-speech synthesis, 2- and 3-D graphics, and Web serving and interaction.
Squeak's easy-to-use graphical interface and its object-oriented approach make it an appealing development environment for educators. A pointer device such as a mouse is required as with all Smalltalk programming environments. The original mouse used with Smalltalk required three buttons each labeled yellow, red, and blue, which is still required today. If a three-button mouse is not available, it must be simulated using another method. For example, the Macintosh-based Squeak environment uses a single-button mouse so the functions are determined by context. This means that if the mouse is placed over a certain area of the screen or another key is pushed at the same time, a menu is activated.
The Squeak programming environment is not the same as the Squeak language developed by Rob Pike and Luca Cardelli in 1985.