Define the purpose of a KPI visualization in Qlik Sense.

A KPI (Key Performance Indicator) visualization in Qlik Sense is specifically designed to instantly display key performance indicators for essential metrics. This type of visualization is crucial for business analysts and decision-makers, as it allows them to quickly assess the performance of their organization against predefined goals and targets.

KPI visualizations are effective in presenting high-level overviews of critical metrics such as sales figures, customer satisfaction scores, and operational efficiency. Their primary function is to provide at-a-glance insights, enabling users to monitor the health of their business at any given moment.

In contrast, the other options focus on different aspects of data visualization. For instance, visualizing historical data trends is about understanding patterns and changes over time but does not center specifically on KPIs. Similarly, presenting detailed analytics reports involves deeper narratives and insights that go beyond the immediate indicators of performance. Finally, providing a comparative analysis over time emphasizes the relationship and changes between data points rather than simply showcasing the current performance metrics. Thus, while all these functions are valuable in data analysis, the specific purpose of a KPI visualization is to highlight essential performance metrics instantly.