What is Node.js and what does it consist of?

Node.js is a JavaScript runtime environment built on Google's V8 engine. It allows running JavaScript on the server, extending the language's capabilities beyond the frontend.

Main components of Node.js:

• V8 — the engine that compiles and executes JavaScript code.
• libuv — a library that provides asynchronous I/O and event loop.
• Core modules — built-in modules for working with the file system, network, streams, etc.
• Event Loop — a mechanism for handling events and asynchronous operations.

Example of a simple HTTP server in Node.js:

const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello, Node.js!');
});

server.listen(3000, () => {
  console.log('Server running at http://localhost:3000/');
});

Thus, Node.js combines the JavaScript engine with system capabilities for creating server-side applications.