The design of web user interfaces has been growing significantly in recent times thanks to libraries like react, Angular, Vue. They allow you to create awesome UI components, but have a great drawback: their components are not interoperable. Web components enable you to overcome this drawback by using a set of standard technologies. The book drives you in the exploration of these technologies with a practical approach. It describes how to create custom elements; how to protect their internal behavior by leveraging the shadow DOM; how to simplify the UI definition through HTML templates. Also, you will discover how to distribute and use your web components and how to leverage libraries and tools to develop them.