Web Development and Content Management Systems Rely on PhP, HTML, Javascript, MySQL and CSS to function. These are the most common languages in modern Web Development.
Instead of building your own system for creating web pages, storing images, and other functions, the content management system handles all that basic infrastructure stuff for you so that you can focus on more forward facing parts of your website.
A content management system, often abbreviated as CMS, is software that helps users create, manage, and modify content on a website without the need for specialized technical knowledge.
In addition to HTML, other markup languages support the use of CSS including XHTML, plain XML, SVG, and XUL.