HTML is the standard markup language for creating web pages. It describes the structure of a web page semantically and originally included cues for the appearance of the document.
CSS is a style sheet language used for describing the presentation of a document written in HTML. CSS describes how elements should be rendered on screen, on paper, in speech, or on other media.
JavaScript is a high-level, interpreted programming language that conforms to the ECMAScript specification. It is a language that is also characterized as dynamic, weakly typed, prototype-based and multi-paradigm.
Expand/collapse widgets help organize content efficiently by hiding details until users need them. This improves page load performance, reduces visual clutter, and enhances user experience by allowing users to focus on relevant information.