Which operations and functions in the code are asynchronous?

In Node.js, asynchronous operations are those that do not block the main execution thread and allow work to continue while a long task is in progress. Such operations include:

• Input/Output (I/O): reading and writing files, working with databases, network requests (HTTP, TCP).
• Timers: setTimeout, setInterval.
• Working with streams.
• Asynchronous functions and promises, which make writing asynchronous code more convenient.

Example of asynchronous file reading:

const fs = require('fs');

fs.readFile('file.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

Here, the file reading is asynchronous, and the main thread is not blocked while the file is being read.