What does Journey History track over time?

Journey History in Salesforce Marketing Cloud tracks how contacts interact with journeys over time, which includes the engagement rates of those contacts. This feature provides insights into how participants are responding to the various elements of a journey, such as emails, SMS messages, or other touchpoints. By analyzing these engagement rates, marketers can assess the effectiveness of their customer journeys, helping them optimize communication strategies and improve overall campaign performance.

The other options do not align with the purpose of Journey History. Journey folder size pertains to the organization of assets within Marketing Cloud, the number of subscribers relates to the total count of individuals in a marketing database rather than their journey-specific actions, and the marketing budget is an entirely separate aspect of campaign management that does not involve tracking individual interactions within journeys.