In Salesforce Data Cloud platforms, lookback window data segmentation defines the timeframe for analyzing past user activities to create audience segments. It determines how far back historical events, behaviors, or transactions are considered when targeting users. For example, a 30-day lookback window includes only user interactions from the past 30 days, ensuring segmentation rules remain relevant. Platforms offer customizable windows ranging from 7 days to over a year, depending on business needs. Short-term windows (7-30 days) focus on recent engagement, such as website visits or product views, making them ideal for retargeting and personalized marketing. Mid-term windows (30-90 days) capture broader interactions like purchases or app usage, useful for customer retention. Long-term windows (90+ days to a year or more) track loyalty trends and enable predictive analytics. The impact of lookback window data segmentation depends on its length—shorter windows allow for real-time segmentation but may exclude infrequent interactions, while longer windows provide deeper insights but may include outdated data. Businesses often customize lookback windows based on their objectives, data availability, and compliance regulations such as GDPR or CCPA to ensure accurate segmentation, improved engagement, and optimized marketing efforts.