A Key Performance Indicator (KPI) is a key measurement that can be used to measure the success or performance of, for example, an advertising campaign. KPIs are set as targets.

Some examples of KPIs in online marketing:

• traffic,
• Impressions,
• cost per click,
• cost per conversion,
• number of Leads

Find more information about the topic on Piwik PRO blog:
42 KPI ideas for your product analytics