This document introduces Gatsby.js, a static site generator built with React, Webpack, and GraphQL. It discusses static site generators and their benefits like fast load times, simplicity, and reliability. Gatsby allows building lightning fast websites, especially for content that doesn't change frequently, like blogs, business sites, and ecommerce sites. The document explains key concepts behind Gatsby like React, Webpack, and GraphQL and demonstrates Gatsby by reviewing the author's blog built with it. While Gatsby is still early, its benefits include optimized loading, best practices out of the box, and flexibility of a React application.