Hard to precisely describe, so I'll go by example:
- Sheldon Brown's Bicycle Technical Info, the online bible for bicyclist [1]
- Guerrilla guide to CNC and resin casting, incredibly documented ressource to get stated in casting [2]
- Jeff Varasano's Famous New York Pizza Recipe, or everything about making pizza at home [3]
Any such foundational webpage for your hobby?
[1]https://www.sheldonbrown.com/
[2]https://lcamtuf.coredump.cx/gcnc/
[3]https://www.varasanos.com/PizzaRecipe.htm