Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation (that is, the look and formatting) of a document written in a markup language. wikipedia.org

HyperText Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages. wikipedia.org

Bootstrap is a popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web. wikipedia.org

Sass (Syntactically Awesome Stylesheets) is a Cascading Style Sheets (CSS) metalanguage that is interpreted into CSS. wikipedia.org

The front end is responsible for collecting input in various forms from the user and processing it to conform to a specification the back end can use. The front end is an interface between the user and the back end. wikipedia.org

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles. wikipedia.org

React is an open-source JavaScript library for creating user interfaces that aims to address challenges encountered in developing single-page applications. wikipedia.org

GitHub is a web-based hosting service for software development projects that use the Git revision control system. GitHub offers both commercial plans and free accounts for open source projects. According to the Git User's Survey in 2009, GitHub is the most popular Git hosting site. wikipedia.org