From Wikipedia..."HyperText Markup Language, commonly abbreviated as HTML, is the standard markup language used to create web pages. Along with CSS, and JavaScript, HTML is a cornerstone technology used to create web pages, as well as to create user interfaces for mobile and web applications."

From Wikipedia...Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language. Although most often used to set the visual style of web pages and user interfaces written in HTML and XHTML, the language can be applied to any XML document, including plain XML, SVG and XUL, and is applicable to rendering in speech, or on other media.

From Wikipedia...JavaScript is a high-level, dynamic, untyped, and interpreted programming language. It has been standardized in the ECMAScript language specification.

From Ross...HTML and Javascript are the basic technologies that execute client side in an application that uses a web browser as the user interface. CSS controls formating and rendering styles on the HTML page. Javascript controls action and interaction in the browser that does not require control to be returned to the server for the page to be refreshed or a database accessed.