Front-end

In software engineering, the terms frontend and backend (sometimes written as back end or back-end) refer to the separation of concerns between the presentation layer (frontend), and the data access layer (backend) of a piece of software, or the physical infrastructure or hardware. In the client–server model, the client is usually considered the frontend and the server are usually considered the backend, even when some presentation work is actually done on the server itself.
— Wikipedia

I get some fundamentals articles from Frontend Developer Roadmap

I also have own plan to learn frontend development.

Source of articles and materials:

• HTML, note with collection of articles and materials about HTML.
• CSS, about CSS.
• JavaScript, about JavaScript.