What information does the legend at the bottom of the waterfall provide?

The legend at the bottom of the waterfall provides W3C page-level metrics and resource timing. This information is crucial for understanding the performance of web pages as it breaks down the loading times of various resources involved in rendering the page.

W3C page-level metrics allow users to see detailed timing information that includes the time taken for different resource types such as images, scripts, and stylesheets to load. Knowing these timings helps identify bottlenecks and analyze the overall user experience during page load. By observing resource timing in the waterfall, users can see which resources are taking the longest to load and make decisions around optimization strategies based on this data.

The other options do not pertain directly to the waterfall legend. Server location details are typically not conveyed through this visual representation. User feedback scores are qualitative data that do not impact the timing of page resources, and database query performance relates to backend processing, which is not visible in the waterfall view.