HTML is a coding language that most people use to build websites. In fact, if you already have a website, you have probably already dabbled in HTML coding a bit.
Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web Designed for everyone, everywhere. Bootstrap makes front-end web development faster and easier. It's made for folks of all skill levels, devices of all shapes, and projects of all sizes
Responsive designs are created by combining one well-crafted HTML page with multiple sets of CSS styles, and then using media queries to target each set of styles. Media queries are CSS rules that inform a web browser about which set of styles should be applied to the page when the browser window is within a specified size. Essentially, media queries cause the styles applied to a page to change based on the width of the browser window.