The "header-only" is actually accidental. It's all C++ template classes, which must be fully defined at their declaration site (so the header). When using the

The "header-only" is actually accidental. It's all C++ template classes, which must be fully defined at their declaration site (so the header). When using the template, the compiler will generate the code needed by "instantiating the template" (for lack of a better word). The other advantage is that it requires no build system to include in your project.