HTML 5 is a software solution stack that defines the properties and behaviors of web page content by implementing a markup based pattern to it.
Cascading Style Sheets (CSS) is a style sheet language used for describing the look and formatting of a document written in a markup language. CSS3 is a latest standard of css earlier versions(CSS2).
Sass is the most mature, stable, and powerful professional grade CSS extension language in the world. It reduces repetition of CSS and therefore saves time.
PHP is a server side scripting language. that is used to develop Static websites or Dynamic websites or Web applications.
Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.