1: The Event Loop is a C program that orchestrates or co-ordinates the exicution 
of synchronous and asynchronous code in Node.js

2: It co-ordinates the execution of callbacks in six different queues

3: They are nextTick, Promise, Timer, I/O, Check and Close Queues

1: We use process.nextTick() method to queue into the nextTick queue.
2: We resolve or reject a Promise to queue into the Promise queue.
3: we use setTimeout or setInterval to queue into the timer queue.
4: Execute an async method to queue into the I/O queue.
5: Use setImmediate functions to queue into the check queue.
6: Attach close event Listeeners to queue into the close queue.