If you are looking to learn web development online, there are more than enough resources out there to teach you everything you need to know, which sometimes might overwhelm you but get into it. Here are some of my best picks:

‣ Mozilla Web Docs (MDN)

MDN Web Docs, previously Mozilla Developer Network and formerly Mozilla Developer Center, is a documentation repository and learning resource for web developers used by Mozilla, Microsoft, Google, and Samsung. The project was started by Mozilla as a unified place for documentation about open web standards, Mozilla's own projects, and developer guides. MDN Web Docs content is maintained by Mozilla and Google employees and volunteers (community of developers and technical writers). Topics include HTML5, JavaScript, CSS, Web APIs, Django, Node.js, WebExtensions, MathML, and others.

These are some really well curated documents and you should definitely refer to them while learning web development.

You can find them here

‣ The Odin Project

The Odin Project is a great place to jumpstart your career in web development with a full stack curriculum approach that is backed up by an open-source community. The curriculum is made up of a collection of online tutorials, blogs, and courses. For example, there is a web development 101 course made up of lessons that start and the basics and end with you building a practical web application. So you will have opportunities to build portfolio-worthy projects alongside a community of developers.
You can find it here.

‣ Shay Howe's Book for Learning HTML and CSS

It is a really well written book and I personally refer to it whenever I need any help related to HTML and CSS. It makes use of codepen.io.
You can find it here.

‣ w3schools

It is also one of the best resource to learn web development and master the concepts.
You can find it here.

My best tip for all the newbies would be that don't get stuck in tutorial hell and if you don't know what that is, you can read my previous article which you can find here.

Hopefully, these web developer resources can help you along the way. Feel free to share some of your favorite online resources in the comments below.

Keep Learning! Keep Coding!