Yes, Node.js is single-threaded in the sense that it executes JavaScript code on a single thread. The JavaScript runtime (V8 engine) used by Node.js operates in a single thread, meaning only one operation is processed at a time within this thread. This might seem restrictive, but Node.js uses a non-blocking, event-driven architecture to manage many operations concurrently.

However, Node.js is built on libuv, a library that handles I/O operations in the background and uses a pool of threads to manage some tasks. Even though the event loop and JavaScript execution run in a single thread, Node.js achieves concurrency and high scalability through its use of asynchronous programming and efficient task delegation.

• Single-threaded means Node.js executes JavaScript code in one thread at a time.
• Non-blocking I/O allows multiple operations to run in parallel without waiting for each one to complete, making it fast and efficient.
• Event-driven means Node.js listens for events (like file reads or HTTP requests) and processes them when they are ready, instead of waiting for each task to finish.
• The event loop is constantly running, checking for completed tasks and moving the program forward without waiting.Even though it’s single-threaded, Node.js can manage many tasks at once using the event loop and background threads for I/O-heavy operations.