the right place to start with the most fundamental basics.
Can somebody guide me to the place where the most fundamental basics
like terms
node
flow
deploying
LTS
npm-module
are explained?
Does there exist a website that has graphics that make visible what the basic principles are?
If you are wanting to create a Node for Node-RED, then those docs do assume you are familiar with the basic concepts of Node-RED as it isn't the sort of task someone brand new to Node-RED would tackle.
I am surprised that no one has pointed you to the About section of the documentation. It should begin to clarify the most basic terminology for you. You are right to notice that "node" and "flow" are terms of art in flow-based programming, but that is no different than giving specialized meaning to words like "note" and "scale" in music, and so on.
Have you installed Node-Red on a computer and started it up?
You point your browser to the Node-Red editor using the IP address and port 1880 - eg 192.68.1.11:1880
(maybe localhost:1880 or 127.0.0.1:1880 will work if Node-Red is installed on the same machine as the browser, such as a PC.)
It should display a web page something like this:
The left hand column is the palette of available nodes. In the middle is a flow which I have created by dragging an Inject node and a Debug node into the main area and drawing a connection "wire" between them to define the flow of data.
At the top right is the Deploy button. It's red because I have not yet deployed (= saved) the flow.
If I deploy the flow and click the square at the left of the Inject node, the data "Hello World" will travel to the Debug node and appear in the debug tab of the right hand column.
You have the right idea about nodes though, graph theory is where it all starts.
Nodes - in Node-RED do the hard work. They are a collection of code that typically processes an incoming "message". If you are looking at creating your own node, you also need to understand that Nodes (with a capital) are packages of code with specific structures. But we also refer to nodes (small n) as an instance of a Node - that bit is confusing unfortunately. So you install a Node package (like node-red-contrib-uibuilder for example) to Node-RED and then you drag an instance of one of the nodes (small n) defined in the package onto your flow and then deploy it.
Wires - would be the "edges" in graph theory. They connect together the nodes. "Messages" run through the wires between nodes.
Messages - are chunks of data (JavaScript Objects strictly speaking) that are passed from one node to the next (that isn't actually what really happens and there are some subtlties related to how Node.js/JavaScript works).
Flows - are simply collections of nodes and wires. There is some overloading of the term though as the word applies to all of the nodes and wires in a Node-RED instance but it is also used to describe the nodes and wires that are collected into a visual tab in the Editor.
Editor - is the UI where you do your authoring of the logic using nodes and wires. It is the administrative interface for Node-RED
Package - is a collection of files published to npmjs.org (typically). In Node-RED, it contains everything needed to define one or more nodes.
Module - is a specific programming construct used in Node.js. You "export" some stuff in your module and you "import" it elsewhere. In Node-RED it is this capability that lets NR draw together different people's nodes into a single application.
The structure of a Node package is quite particular and you will need to understand something about the way that modules work in Node.js in order to understand the different parts of a Node and how everything works together. You also need to understand the difference between the back-end (server) part of Node-RED and the front-end(s), the Editor in this case. The back-end runs on a server device and the front-end runs in a browser.
Threw that together quickly so I hope it makes sense?
