HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and structure of web content. "Hypertext" refers to links that connect web pages to one another, either within a single website or between websites. HTML uses "markup" to annotate text, images, and other content for display in a Web browser. HTML markup includes special "elements"
MDN HTMLCascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in HTML or XML. CSS is among the core languages of the open web and is standardized across Web browsers according to W3C specifications. Previously, development of various parts of CSS specification was done synchronously, which allowed versioning of the latest recommendations. You might have heard about CSS1, CSS2.1, CSS3. However, CSS4 has never become an official version.
MDN CSSThe Document Object Model (DOM) connects web pages to scripts or programming languages by representing the structure of a document—such as the HTML representing a web page—in memory. Usually it refers to JavaScript, even though modeling HTML, SVG, or XML documents as objects are not part of the core JavaScript language. The DOM represents a document with a logical tree. Each branch of the tree ends in a node, and each node contains objects. DOM methods allow programmatic access to the tree. With them, you can change the document's structure, style, or content.
MDN DOMJavaScript (JS) is a lightweight, interpreted, or just-in-time compiled programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB and Adobe Acrobat. JavaScript is a prototype-based, multi-paradigm, single-threaded, dynamic language, supporting object-oriented, imperative, and declarative (e.g. functional programming) styles. Read more about JavaScript.
MDN JavaScriptIn Summary of the Documentation all this similar and different reference materials. Starting with HTML it is the one that has similarities with other documentation even DOM. where as Javascript can access elements of HTML in DOM.