MDN Web Technology Reference
In the HTML the Mozilla Developer Network talks through the basics of HTML. Html is a markup language that defines the structure of the content. It contains a series of elements, tags, attributes, and more. In the CSS the Mozilla developer Network explains CSS and what is the CSS function. CSS is not a programming language and it is not a markup language. It is a stylesheet language and web developers use CSS to selectively style HTML elements. I think I would use both information because it helps me with studying HTML and CSS more. Also, I think it is a very trusted resource and helps web developers or anyone with a programming language.