Scheme is a clean and fairly small but powerful language, suitable for use as a general-purpose programming language, a scripting language, an extension language embedded within applications, or just about anything else.
Scheme was designed to lend itself to a variety of implementation strategies, and many implementations exist--most of them free software. For Scheme you'll find straightforward interpreters (similar to simple interpreters for BASIC or Tcl), compilers to fast machine code (similar to most compilers for C or Pascal), and compilers to portable interpretive virtual machine code (similar to most compilers for Java).
Several extended implementations of Scheme exist, including our own RScheme system, an extremely portable implementation of Scheme with an integrated object system and powerful extensibility features.
This book is written in Texinfo format, the format used for GNU documentation, so that it can be printed out as a hardcopy document, browsed online as an info document (with the Info browser, or the Info system for the Emacs editor), or converted automatically to HTML format for browsing with a web browser. Whichever way you're reading this book, welcome to Scheme.