Original subtitles

Now before diving into some NodeJS code,

let's do a high level overview

of what NodeJS actually is,

what we use it for and why we use Node

instead of other technologies.

So, the official definition is that

NodeJS is a JavaScript Runtime

built on Google's open-source V8 JavaScript engine.

Now, what does that actually mean?

Well, let's start by trying to understand

what the JavaScript Runtime

and the V8 engine actually are.

So, you have probably already used JavaScript before

and it was probably always just inside a browser, right?

Because any browser natively understands

HTML, CSS, and JavaScript and no matter

if you write vanilla JavaScript or some

JavaScript framework like React or Angular code,

that's all just JavaScript

that gets executed right in the browser.

So, in this case, the browser

is then the JavaScript Runtime.

But, what if we could take JavaScript

out of the browser and simply execute

or JavaScript code somewhere else without

all the restrictions that we have in the browser?

Well, it turns out that we actually can.

And the solution for this, as you can guess,

is called NodeJS and so Node JS

is just another JavaScript Runtime.

It's just like a container, like an environment,

in which a program written in JavaScript

can be executed, but outside of any browser whatsoever.

All right, it's actually a bit more complex

than this, of course, but for now, this is enough.

Now, who actually does execute

the code if not the browser?

And that's where the V8 engine

developed by Google comes into play.

Because that is exactly where JavaScript code

will be parsed and run in NodeJS, okay?

So, I hope that now the definition of NodeJS

being a JavaScript Runtime on the V8 JavaScript engine

makes a lot more sense and again,

this is just a very high level overview

of what Node is and how it works.

We are gonna go into a lot of detail

about how Node really works behind the scenes

right in the next section, but at this point,

I just want you to get a quick overview

so that you can start learning the fundamentals

of NodeJS in practice throughout this section.

Anyway, now that we have JavaScript

outside of the browser in a kind of

stand alone environment which just NodeJS,

we can do so many more things with JavaScript

that were completely impossible before

like accessing the file system,

or better networking capabilities

are not possible with NodeJS

and all these factors together give us

the perfect conditions for using NodeJS as a web server

meaning that now we can finally use JavaScript

on the server side of web development

in order to build fast, highly scalable

network applications for powering the back-end

all for websites or web applications.

And this is absolutely fantastic

and game-changing for web development.

So, let's now take a look at some use cases for Node

and why it's such a great fit for back-end development.

And the first thing that we need to talk about

is the fact that Node applications

are so fast and so scalable because NodeJS

is single threaded based on

an event driven, non-blocking I/O model

which makes NodeJS very lightweight and efficient.

Now, that, of course, sounds super complicated,

I know, but once more we're gonna talk about

exactly what all of this means

a little late in the course.

But, for now, just keep in mind

that Node is perfect for building super fast,

and scalable data-intensive web applications.

And that makes NodeJS a perfect fit for building

all different kinds of applications like

building an API with a database behind it

and preferably a non-relational NoSQL database like MongoDB

and this is actually exactly what we're gonna do later

in this course as we dive deeper and deeper into NodeJS.

But, there is, of course, all sorts of other apps

that we can build like data streaming applications

such as YouTube or Netflix, real-time chat apps,

or even server-side web applications

where the entire content is simply generated

right on the server, so as you see,

the possibilities really are endless.

But, there is actually, also, a type of apps

that we should not build with Node.

And this is when our app needs

some super heavy server-side processing

like having image manipulations, video conversion,

file compression or anything like that, all right.

And you will learn why that is once we dive deeper

into how Node actually works.

So, in this case, we're better off

using something like Ruby on Rails, PHP, or Python.

Because NodeJS just wasn't developed

for these use cases and although there are solutions

for dealing with them, we should always use

the right tool for the task at hand.

Okay, so these are the types of applications

that we can and cannot build using NodeJS.

And if you choose to use Node,

well, then you are in good company because

many top companies like Netflix, Uber, PayPal,

Ebay and many many more have already started using

NodeJS which really proves that the technology

is stable enough at this point to be used in production.

Now, of course there are more reasons for using Node,

and the biggest one is probably that using

the same language across your entire stack

both on the front-end and the back-end

is a lot easier for you or for your team.

First, you don't have to learn

a new programming language for building

your back-end and, also, you don't have to

keep switching back and forth between language

which will make the entire building process

faster and more efficient.

Believe me, it's really really amazing

to be able to use JavaScript to build

your entire application from start to finish.

It's absolutely fantastic really.

And another great reason for using Node

is that there is a huge library of open-source packages

or modules, as we can also call them,

available for everyone for free.

It's called NPM and you've probably heard of it

or even used it already.

And, of course, we're also gonna start

using packages right in the section.

And, finally, it's also good to know

that there is a huge active community

of Node developers out there that are constantly

improving NodeJS and helping beginners like you.

And, so you can really rely on the technology

for all your projects in the years to come.

Okay, so that was a very brief intro

and overview of NodeJS and some of it's use cases.

So, for the rest of this section,

we will now use Node to create

a very simple web server and build

an extremely simple API, so that

you can get familiar with

the basic principles of Node development.