Safari Developer Tools is a set of built-in features in the Safari web browser that helps developers create and debug websites. It provides tools for inspecting HTML and CSS, monitoring network requests, and testing JavaScript performance. These tools are essential for ensuring that web pages function correctly across different devices and screen sizes. To access Safari Developer Tools, users can enable the "Develop" menu in the browser settings. Once activated, developers can use features like the Web Inspector to analyze page elements, view console logs, and simulate various device environments. This makes it easier to identify and fix issues in web applications.