The Boost libraries provide free peer-reviewed portable C++ source libraries. The emphasis is on libraries which work well with the C++ Standard Library. The libraries are intended to be widely useful, and are in regular use by thousands of programmers across a broad spectrum of applications.

A further goal is to establish "existing practice" and provide reference implementations so that Boost libraries are suitable for eventual standardization. Ten Boost libraries will be included in the C++ Standards Committee's upcoming C++ Standard Library Technical Report as a step toward becoming part of a future C++ Standard.