Non-Blocking I/O

Summary

Node's approach of starting an I/O operation (file read, network call) and continuing to execute other code while it completes in the background, instead of waiting.

• 1Compare a blocking `readFileSync` call to a non-blocking `readFile` callback version.
• 2Learn how libuv's thread pool handles I/O operations behind the scenes.
• 3Understand why this model lets Node handle high concurrency with a single thread.