hjs is an NPM package that integrates Hogan.js templating with Express 3.x, allowing developers to use Mustache-style templates in their Node.js applications. It's designed for developers working with Express 3.x who want to leverage Hogan.js's Mustache templating capabilities for rendering views. The package provides a straightforward way to set up Hogan.js as the view engine in Express applications, complete with support for partials and the familiar Mustache syntax.