This chapter explores the importance of trustworthy data in the cultural heritage field, highlighting its critical role in the preservation and interpretation of historical legacies. Trustworthy data is the foundation for decision making, academic research, and public engagement. Challenges such as authenticity, degrading data, complexity, ethical considerations, and reliability are highlighted. Principles such as accuracy, completeness, consistency, security, and timeliness are fundamental to ensuring the trustworthiness of data. The chapter also discusses the importance of data collection standards, verification processes, and comprehensive documentation, as well as diverse data sources, including archaeological excavations, historical texts, oral histories, and technological advances. Ethical considerations and the challenges of maintaining the trustworthiness of data, such as technological limitations and human error, are also addressed. The chapter concludes with a discussion of the need for ongoing monitoring, updating, and staff training to ensure the reliability and preservation of cultural heritage data.