PHP is a popular general-purpose weakly-typed server-side scripting plus object oriented programming language that is especially suited for web development.
HTML (HyperText Markup Language) is the standard markup language used for structuring web pages and formatting content. HTML describes the structure of a website semantically along with cues for presentation, making it a markup language, rather than a programming language. The most recent revision to the HTML specification is HTML5.
A freely available open source Relational Database Management System (RDBMS) that uses Structured Query Language (SQL). If your issue relates to MySQLi, use the MySQLi tag instead.
CSS (Cascading Style Sheets) is a style sheet language used for describing the look and formatting of HTML (Hyper Text Markup Language) and XML (Extensible Markup Language) documents including (but not limited to) colors, layout, and fonts.
A lightweight open source web application framework that utilizes the MVC architecture to quickly develop web applications.
Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web.