HTML stands for HyperText Markup Language. It is the standard markup language used to create and structure content on the web. HTML elements are the building blocks of web pages and are represented by tags.
CSS stands for Cascading Style Sheets. It is a style sheet language used to describe the presentation of a document written in HTML. CSS controls the layout, colors, fonts, and overall visual appearance of web pages.
JavaScript is a versatile, high-level programming language primarily used to create interactive and dynamic content on websites. It can manipulate the DOM, handle events, make network requests, and much more. It runs in the browser as well as on servers via environments like Node.js.
Responsive design is an approach to web design that makes web pages render well on a variety of devices and window or screen sizes. It uses flexible layouts, flexible images, and CSS media queries to adapt the presentation to different viewing contexts.