My guess is either you went to https://apex.oracle.com and got a free account or Oracle Application Express was already in your company and somebody told you the url you could connect to. For me that is really the power of APEX, you just go to an url and within minutes you created your first app.
Staying within the APEX framework?
Oracle closely looks at all the web technology, makes choices which streams they will follow (e.g. JQuery framework) and implements and tests it so we don't have to worry about a thing.
Going to the next level?
The web is evolving fast, and I mean really fast (!) so maybe you saw something really nice on the web you wish you had in your APEX app, but it's not yet declaratively available... now the nice thing about APEX is that you can extend it yourself by using plugins (see the plugins section on apex.world) or just by writing the code yourself as other web developers do.
Trying new web technology locally
When you want to try those shiny new web things in your APEX app, I recommend trying to get those things working locally first. Last year for example I gave a presentation about Web Components at different Oracle conferences and this year I'll present on Service Workers. All the research I did on those topics where initially not in an APEX context. But how do you get started to try this now?
The first thing you need is a local web server. Depending the OS you're on, you might already have one (e.g. IIS, Apache, ...), if not, here's what I do on OSX.
OSX comes with Python and that allows to create a simple web server.
Open Terminal and go to the directory where you want to test your local files and run:
$ python -m SimpleHTTPServer 8000 (Python 2.7)
$ python3 -m http.server 8000 (Python 3.0)
There're many other ways to have a local web server, see for example this article or a simple web server based on node.js.
To do this development, you probably want some tools; an editor like Sublime or Atom, a CSS and JS preprocessor, Browser extensions, build tools like Gulp etc.
You don't need all those tools, just an editor is fine, but soon enough you want to be more efficient in your development, and tools just help :) Here're some nice articles about different tools: Google Developers - Getting Started, Keenan Payne 13 useful web dev tools and Scott Ge list of web development tools.
Going from custom web development to APEX - use APEX Front-End Boost
So you have your local files developed and next is to integrate them in your APEX app.
You add some code to your APEX pages and upload the files so APEX can see them.
If everything works immediately - great, but most of the time you probably need to make more changes, so you change your local files, test again, upload etc. You could streamline this a bit with setting up a proxy or referencing localhost files while in development... But then you're happy your part of the APEX community...
To ease the above development and integration with APEX, Vincent Morneau and Martin Giffy D'Souza created the excellent APEX Front-End Boost package. The package is using many of the above tools behind the scenes, but it's all integrated in a nice box. This video goes in full detail what the tool is doing for you and how to use it. In short; it fills the bridge of working with a file locally, making it production ready and seeing it immediately in your APEX app :)
In the next post I'll talk about the importance of using https and also setting it up for localhost (also for APEX Front-End Boost).