Flexbox

HTML

HTML stands for Hyper Text Markup Language
HTML is used to create pages which are rendered over the web
HTML is the combination of Hypertext and Markup language
HTML is used to create the structure of web pages that are displayed on the World Wide Web
It contains the essential building-block elements (i.e. doctype declaration, HTML, head, title, and body elements)

CSS

CSS stands for Cascading Style Sheets
It is used to add styles to the webpage
It includes lots of tools to make a website more attractive
It also has options of selecting particular portion of a webpage through selectors
It helps in enhancing the user interface

Javascript

Javascript is a lightweight interpreted programming language
It is cross platform scriptingb language for webpages
It is used to add the logic to your webpage
It helps in building client-side dynamic webpages
Javascript and java are completely different from each other

PHP

PHP stands for Hypertext Pre-processor
It is a server-side scripting language
It is embedded in HTML
It is used to manage dynamic content,database,session tracking etc.
It includes many functions and many useful variables to store data