MDN- Mozilla Web Docs-CSS Flexible Box Layout
MDN is a site that is meant as a resource for web developers that is curated by web developers. It is set up much like W3 Schools in which it will walk through all the different styling elenments with HTML and CSS examples.
W3.org-CSS Flexible Box Layout Module Level 1
This is a learning module put out by the W3. It is designed to teach developers about flexible design and demonstrate best practices. There are also testing modules that a developer can participate in to test their coding ability.
CSS-tricks- A Complete Guide to Flexbox
This site is set up as a learning module for flexbox. The layout and presentation are more modern and designed for a younger demographic of developer. It is easy to follow and feels less intimidating than Mozilla or W3.org.
Summary
It seems that the web developer community is a community of collaboration. It reminds me very much of the teaching community. We are constantly sharing information with others. The idea of collaboration vs proprietary information is a great one. The challenge then becomes less about access to information, but the sorting out of the best ideas and resources.