HTML Tags and Attributes references 
found by y'all (and others)

Site Recommendations
http://www.w3schools.com/ "true brilliance","My life was a dim light until I discovered w3schools.com"
http://www.yourhtmlsource.com/myfirstsite/ very insightful because it categorized the tags into different areas where they might be useful
http://www.htmldog.com/ It has short tutorial sections (Beginner, Intermediate & Advanced)...
https://www.codecademy.com/learn/web It contains many small sections where the topic is explained and then you have to code what it tells you to. 
http://serendip.brynmawr.edu/serendip/htmlprimer.html  Good single page listing of main tags/definitions/colors
https://developer.mozilla.org/en-US/docs/Web/HTML/Element a handy element reference website
http://www.quackit.com/html/codes/ explains the functions of tags clearly and let you try them out on the webpage
http://www.simplehtmlguide.com/cheatsheet.php I found the information and guidance on the page: Amazing . It was really good and give a ton of information into HTML tags.
http://www.way2tutorial.com/html/html_basic_tags.php website is truly fabulous. All the tags are organized neatly in the sidebar.
http://learn.shayhowe.com/ The most well designed, easy to navigate, and helpful site I found 
https://duckduckgo.com/?q=html+cheat+sheet&t=ffab&ia=answer&iax=1 A very quick cheatsheet
http://www.webmonkey.com/2010/02/html_cheatsheet/ Another cheatsheet
http://webdesignfromscratch.com/html-css/html-tags/ tells you which ones you should try and restrain from using, and which ones you should absolutely not use, especially blink and marquee
https://en.support.wordpress.com/beginning-html/ I FOUND SUPA SUPA COOL INFO ON DIS PG
https://www.marcaria.com/ws/en/articles/learn-about-domains-and-html A good set of (mostly university) for simple explanations of web concepts.

Other main HTML/CSS sites

http://html.com/ Decent reference and a good number of tutorials
https://www.tutorialspoint.com Innovative tutorials site for a vast number of tutorials
https://websitesetup.org/html5-periodical-table/ An interesting and quick guide to HTML tags

Data sites

https://www.springboard.com/blog/free-public-data-sets-data-science-project/  A short list (19) of sites offering (free?) large datasets