What language does Node.js use?

Node.js primarily uses JavaScript as its programming language. JavaScript is a widely-used and versatile language that can run on both the client-side (in web browsers) and the server-side (with Node.js). Integrating JavaScript as the language of choice for Node.js allows developers to write code using a consistent language across different environments, making it easier to share and reuse code. Additionally, JavaScript's event-driven and asynchronous nature aligns well with the single-threaded, non-blocking architecture of Node.js, enabling it to handle high levels of concurrency and scalability efficiently.