HTML, or HyperText Markup Language, is the backbone of any website, defining its basic structure. It uses tags to create elements like headings, paragraphs, and links. HTML5, its latest version, introduces new features aiding in semantic web design.
CSS, or Cascading Style Sheets, determines a website's aesthetics: layout, colors, and fonts. By separating presentation and content, it improves accessibility and offers flexibility in defining presentation characteristics. CSS3 is the latest version with enhanced features.
Bootstrap is an open-source CSS framework focused on responsive, mobile-first web development. It provides pre-defined classes and templates for quicker web development and enables easy creation of designs that adapt to different screen sizes.