HTML which in full means Hyper Text Markup Language, is a language for structuring the content of a web page, it enables a web browser to recognize the various elements and how they are structured.

CSS which in full means Cascading Style Sheet, is a language for describing the presentation of a web page, it enables the web browser to know how elements on a web page are to be rendered, it tells the browser how they should look like by describing properties like colours, fonts, margin and paddings etc.

JavaScript is a language for programming a website, it is used to add dynamism to the cotents of a website by allowing users to interact with it and manipulate it. It is also an interesting tool to use and learn.

PHP which in full means Hypertext Pre-Processor is a powerful server-side (Backend) scripting language for programming how a website interacts with a server.