HTML and CSS are vital parts of web-based interfaces. HTML provides a structure to a document and CSS is used to format it for actual presentation.

In Studio 3 you will be creating a basic web interface for an IoT product. It's important that you learn the basics of HTML and CSS prior to the studio. Even if you have already worked with HTML and CSS, it's recommended that you work through this to review and, possibly, pick up something new.

Khan Academy’s "Intro to HTML/CSS: Making webpages" includes guided lessons that are a particularly good way to learn or review the HTML and CSS concepts relevant for this course. It would be best to work through all sections (Intro to HTML, Intro to CSS, More HTML tags, CSS text properties, Web development tools, CSS layout properties, More CSS selectors, Other ways to embed CSS, and Further learning). Working through all sections will most likely take 2-4 hours. Ideally you should complete at least through CSS layout prior to your studio.