Web Developer Reference GuideIt introduces the basic elements necessary for web application development. This article introduces basic techniques for developing JavaScript, which is a basic technology of web technology, to add dynamic elements, starting with HTML and CSS, and NodeJS, a server-related technology utilizing it, and web applications. It also explains how to make web applications more efficient and cool by using web frameworks like bootstrap, jQuery, and angular JS. As the number of users accessing the web through mobile devices has increased, the popularity of the responsive web has increased. We will also discuss bootstrapping, a front-end framework for web development, to accommodate this trend.