Joe McCourt discusses the introduction of Change Graphs, a new visualization tool designed to help users easily identify and measure differences between identical timeframes, such as comparing data from today with data from the same time yesterday. This tool is particularly useful for detecting changes related to seasonality and is implemented in visualizations on Datadog dashboards, which can be set up through a simple drag-and-drop or API process. Change Graphs focus on highlighting changes in web traffic, login rates, errors, latency, and other key system health indicators, offering an advantage over traditional graphs that may not clearly show significant changes. McCourt emphasizes the immediate visibility of changes, such as increased server-side errors across availability zones, and invites users to try this feature by signing up for a free trial of Datadog.