HTML (Hypertext Markup Language) is the standard language used to create web pages. It provides the structure and content of a web page, including headings, paragraphs, images, links, and more. CSS (Cascading Style Sheets) is a language used to style and layout web pages. It is used to control the colors, fonts, spacing, and other visual elements of a web page. CSS allows you to separate the presentation of a web page from its structure, which makes it easier to maintain and update. Bootstrap is a front-end development framework that is built on top of HTML and CSS. It provides a set of pre-designed components and layout options that can be easily integrated into web pages. Bootstrap makes it easy to create responsive and mobile-friendly web pages, and it also includes a set of JavaScript plugins that can be used to add interactivity and dynamic functionality to web pages.