HTML is HyperText Markup Language.
CSS is a language that describes the style of an HTML document.
JavaScript is a programming language of HTML and the Web.
Why study them?
HTML to define the content of web pages;
CSS to specify the layout of web pages;
JavaScript to program the behavior of web pages.
JavaScript Libraries
JQuery
Angular
React: a declarative, efficient, and flexible JavaScript library for building user interfaces.
Node.js
it is an open source server environment, which allows us to run JavaScript on the server.
Django
it is a high-level Python web framework that makes us easier to build better web apps quickly with less code.