Asynchronous vs Synchronous in NodeJS

So in nodejs the methods are primarily nonblocking and by that I mean that the code inside of them is executed without stopping the execution for the other parts of the program until it finishes it's current operation.

A famous example would be reading a file using the fs module:

const fs = require('fs');
const data = fs.readFileSync('/file.md');

Here the second line will block the execution until it finishes the current task at hand, so this is Synchronous.

The counterpart would be the Asynchronous:
const fs = require('fs');
fs.readFile('/file.md', (err, data) => {
if (err) throw err;
});

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