Node.js is a powerful JavaScript runtime built on Chrome’s V8 JavaScript engine, designed to build scalable network applications. Unlike traditional languages that use threading for concurrency, Node.js uses non-blocking, event-driven architecture, allowing for the development of efficient and real-time applications, especially on the server-side.

In a Node.js crash course, one would explore how to utilize this platform to write server-side code using JavaScript, thus unifying web application development around a single programming language, rather than different languages for server and client-side scripts. The course delves into Node.js core modules, asynchronous programming patterns, handling HTTP requests, and interfacing with databases. It equips developers with the skills to leverage Node.js for building APIs, streaming applications, and handling real-time data with WebSockets, while also introducing the npm ecosystem, which provides thousands of libraries for various use cases.