When W3Fools started years ago, the state of documentation for developers was poor.
The Mozilla Developer Network was around but it did not have much support at the time.
Developers often use W3Schools only because it is at the top of search results.
Since W3Fools launched, the MDN has seen a lot improvements from the community.
Further, the W3C has created Web Platform Docs as the authoritative resource for documentation.
These are community driven efforts maintained by developers who continue to work in the field.
W3Schools still has issues but they have at least worked on the primary concern developers had. For many beginners, W3Schools has structured tutorials and playgrounds that offer a decent learning experience. However, it would be a mistake to continue your education without learning from more reputable sources, so when you're ready to level up, move on.
Many developers swear by the content provided by the MDN.
The WPD site is also growing and is even convened by the W3C itself for this effort.
The best way to find good resources are to ask other developers where or from whom they learn and get information.
Some exemplary places to learn from are:
There are also chatrooms full of people willing to help point you to the right places or even help out with your exact issue.
Here are a handful of trusted rooms on Freenode IRC:
Stay curious, stay interested
The web is an incredible platform that few people understand in its entirety.
It’s yours to dive into and explore.
Don’t forget to share your knowledge and passion with others; it’s the best part.