Where are the content types? The variables? The settings?

The easy answer: nowhere.

Quanta has no "content types", because content in Quanta is contained in JSON files that can be whatever, depending how you call them.

 Just like Schrödinger's cat, a typical thought experiment from quantum physics, in Quanta you can decide to have a single entity acting as a News Item, an User, a Variable, or whatever else... at the same time.

Let's make a rapid example.

{"permissions":{"node_add":"admin",
"node_edit":"admin",
"node_delete":"admin",
"node_view":"anonymous"},
"name":"apple",
"teaser":"A sweet,
 tasty,
 and crisp apple.",
"author":"aldo",
"body":"The apple tree (Malus domestica) is a tree that sheds its trees in the rose family best known for its sweet,
 tasty fruit,
 the apple. It is grown worldwide as a fruit tree. The tree originated in Central Asia. Apples have been grown for thousands of years in Asia and Europe. They were brought to North America by European settlers. Apples have religious and mythological significance in many cultures.Apples are generally propagated by grafting,
 although wild apples grow readily from seed. Apple trees are large if grown from seed,
 but small if grafted onto roots (rootstock). There are more than 7,
500 known cultivars of apples,
 with a range of desired characteristics. Different cultivars are bred for various tastes and uses: cooking,
 eating raw and cider production are the most common uses. Trees and fruit are attacked by fungi,
 bacteria and pests. In 2010,
 the fruit's genome was sequenced as part of research on disease control and selective breeding in apple production.",
"title":"Apple",
"thumbnail":"apple.jpg",
"timestamp":1515862800,
"status":"node-status-published",
"price":"0.99",
"discount":"12%",
"stock":"150"}

As you see, this is a basic representation of an Apple.

What can we call this... a node? A product? a fruit

It's none of them, and all of them at the same time.

But for now, let's imagine we are using this JSON for a fruit data website, describing apples.

What if we want to make this apple a product we can sell in an ecommerce site?
Well, we could just adapt the JSON to this:

{"permissions":{"node_add":"admin",
"node_edit":"admin",
"node_delete":"admin",
"node_view":"anonymous"},
"name":"apple",
"teaser":"A sweet,
 tasty,
 and crisp apple.",
"author":"aldo",
"body":"The apple tree (Malus domestica) is a tree that sheds its trees in the rose family best known for its sweet,
 tasty fruit,
 the apple. It is grown worldwide as a fruit tree. The tree originated in Central Asia. Apples have been grown for thousands of years in Asia and Europe. They were brought to North America by European settlers. Apples have religious and mythological significance in many cultures.Apples are generally propagated by grafting,
 although wild apples grow readily from seed. Apple trees are large if grown from seed,
 but small if grafted onto roots (rootstock). There are more than 7,
500 known cultivars of apples,
 with a range of desired characteristics. Different cultivars are bred for various tastes and uses: cooking,
 eating raw and cider production are the most common uses. Trees and fruit are attacked by fungi,
 bacteria and pests. In 2010,
 the fruit's genome was sequenced as part of research on disease control and selective breeding in apple production.",
"title":"Apple",
"thumbnail":"apple.jpg",
"timestamp":1515862800,
"status":"node-status-published",
"price":"0.99",
"discount":"12%",
"stock":"150"}

See the bold values? price, discount, stock... They were not there before. But now our apple is ready to be sold! 

That would be hardly possible in any CMS using a strict ER database, where you would have to create a new table containing the new fields, and then join the two tables in your queries. 

In Quanta, you can freely add, and remove values to JSONDataContainer items.

Now, how do you choose how to render your data? You will not want an "encyclopedic" version of your apple looking the same as it's ecommerce "product" version, right?

That's where qtags come very handy.

Variables, settings, permissions, everything in Quanta works with the same concept and under the same model.

A variable, in example, could be something like this: 

{"name":"count_site_visitors",
"title":"Count site visitors",
"body":"This variable contains the number of visitors that have visited the site since the beginning",
"value":"14031"}

Or something like this: 

{"name":"count_site_visitors",
"title":"Count site visitors",
"body":"This variable contains the number of visitors that have visited the site since the beginning",
"value":"14031"}

..still a JSON file, with no pre-defined structure, to which you can plug / unplug new fields anytime.

Remember when I said you don't have "content types" on Quanta? 

Actually, if you really really love the concept of "content type" you could just add a "type" variable to the JSON file. 

I never had the need to do it so far... :-)