The Boost library brings useful features to C++ that are not yet in STL. For example, the C++17 filesystem library was in Boost for several years. Until the most recent compiler releases, C++17 filesystem required Boost.

Boost install requires several hundred megabytes in general. macOS and Linux users can install from a package manager.

On Windows, installing Boost from the Boost binary distribution takes a lengthy build procedure. Most developers using GCC or Clang on Windows can instead simply install MSSY2 Boost.