Express Handlebars is a Handlebars view engine for Express that adds back support for layouts and partials, which were removed in Express 3.x. It provides smart template caching, asynchronous I/O, and allows easy precompilation of templates for client-side use. The project is aimed at Express developers who want to use Handlebars as their templating engine and need features like layouts, partials, and helpers that integrate seamlessly with Express's view system.