HTML, Hyper Text Markup Language.

Tutorials:

Introduction to Automation: Living beyond yourself.
Web pages, HTML, Javascript and the Internet Of Things (IOT)
(A Google drive collaborative presentation)
Page Tutor

Reference:

HTML Lib Index or <HTML>
Hyper Text Markup Language reference (Microsoft Internet Explorer specific)
Forms
Graphic Extensions
Character Set
Browser support of HTML and known bugs
AOLPress HTML Reference
Automatic reloading of a page
DOM Scripting
AJAX
HTML5 Web Apps

Tools:

See:

Input and Output to Physical Devices from JavaScript
/techref/wayback.htm Better Toolbar Link for WayBack
TCP/IP@
JavaScript@
CSS: Cascading Style Sheet: Scripting Reference
PDF@
Design guidelines

See also:

https://www.youtube.com/watch?v=iX_QyjdctsQ
00:35 - Fieldset
01:43 - Datalist
03:13 - Color Picker
04:11 - Progress Bar
04:52 - Open Graph
07:51 - Sub/Sup
09:18 - Picture
13:19 - Template
https://codesandbox.io/s/m3n33jpy18 Go game
http://jsfiddle.net/codeandcircuit/6uoyvfs3/ Sample snake game.
http://www.blooberry.com/indexdot/html/index3.htm AWESOME reference on HTML (thanks to Julian Haight)
http://code.google.com/p/doctype/wiki/HTMLElements
http://msdn.microsoft.com/en-us/library/ms533029(VS.85).aspx Microsoft Workshop only IE
http://www.seomoz.org/blogdetail.php?ID=1282 5 HTML elements you probably never use (but perhaps should): <address>, <q> for multi-level quotes (not in IE), <optgroup> for sub options in selects, <acronym> or <abbr> combined with the title attribute for "popup" definitions, and <fieldset> and <legend> for grouping form fields.
http://www.visibone.com/colorlab/ Color picker / wheel.
http://www.grc.com/menu2/invitro.htm Menuing system in a style sheet (no Javascript). Graceful degradation, supports most all browsers even old ones."
http://web.archive.org/web/20070715174227/http://www.bigbaer.com/css_tutorials/css.float.html.tutorial.htm Foating allows tables or other elements to act like images in the way they will move when the screen resizes.
http://www.zdnet.com/devhead/resources/tag_library/ AWESOME reference on HTML and what browsers support what tags.(thanks to Kevin Blain) WAS: Now dead: Did anybody cache it?
http://www.bigbold.com/snippets/posts/show/2011 DHTML Tabs. Section headings on a web page become tabs along the top.
http://www.drpeterjones.com/colorcalc/index.html Really nice little color tool. Javascript.
http://www.macromedia.com/v1/documents/hs4/html_reference/Dynamic_Documents/ov.htm Dynamic Documents
http://www.macromedia.com/v1/documents/hs4/html_reference/index.htm Very nice quick reference to HTML elements (cached 20040301152700)
http://validator.w3.org/ is a nifty HTML validation tool. Once you validate a page, it tells you a snippet of code to add to the end of a page to get a single-click revalidate of that page. Perhaps it would be nifty to add this revalidate link to the "You can EDIT this page" template.
"Template-Driven Web Pages" in Dr. Dobbs Journal, November 1997 pg 74 by Jay Johansen
The XML revolution promises to bring a new approach to creating data-aware Web environments. Read about it on TechNet at http://www.microsoft.com/ithome/topics/intranet/articles/xml/xml01.htm.
http://www.devguru.com/home.asp
Editing HTML in the browser (with *script, text controls, etc...) see Javascript
http://www.simonstl.com/dynhtml/update/index.html Dynamic HTML: A Primer
DHTML
- http://www.dhtml-guis.com/using cross-browser and cross-platform Dynamic HTML.
- http://www.scottandrew.com/index.php DHTML and JavaScript including cross browser support from Scott Andrew.

Code:

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details
```
<details>
    <summary>Details</summary>
    Something small enough to escape casual notice.
</details>
```
Details
Something small enough to escape casual notice.

Questions:

Interested: