Foreword

The web has come a long way. What started three decades ago as a relatively simple means of publishing, sharing, discovering, and consuming content has evolved into a powerful and flexible application platform supporting a dizzying array of use cases. Meanwhile, its footprint has expanded from desktop computers to devices of all types.

As a result of this gradual transformation, we web developers have been chasing an ever-moving target. Today’s websites are orders of magnitude more complex than their early predecessors, and UI expectations have shot through the roof.

Thankfully, our toolbox has also evolved. The web platform itself has gained hundreds of new capabilities, and successive generations of libraries, frameworks, and tools have steadily advanced the state of the art, helping us meet rising demands.

One major enabler of the web’s transformation in recent years has been the widespread adoption of component-based UI development. Factoring our work into components—each one responsible for the structure, style, and behavior of a slice of the user experience—has helped us manage complexity and build more ambitious sites.

Components can be reused throughout a project or shared across projects, increasing our efficiency. Design systems can be expressed as collections of ready-to-use components, ensuring consistency and freeing teams to focus on product-specific needs.