Key performance indicators (KPIs) are essential benchmarks for evaluating website performance, often used in audience analysis. For a non-commercial website, these KPIs might include elements such as the number of newsletter subscribers, completed forms, calls to a specific number, and orders generated by those calls. Conversely, for e-commerce websites, the main KPI is generally the conversion rate, which represents the percentage of visitors who become customers. Furthermore, KPIs are also used to assess the effectiveness of sponsored link campaigns or other online marketing activities. The field of web marketing relies heavily on KPIs for the precise measurement of the impact of various initiatives. In practice, defining web KPIs often translates into setting up corresponding objectives or events within web analytics tools.