<p>Cloud computing is widely adopted across industries such as finance and government, yet ensuring data security in the cloud remains a significant challenge. This study reviews key data security technologies—including encryption, access control, and privacy-preserving computation—and evaluates their effectiveness through real-world case studies. Findings indicate that no single technology provides comprehensive protection; instead, integrating multiple approaches—such as encryption, zero trust, and threat intelligence—offers a stronger defense. A collaborative, layered security strategy significantly enhances resilience against cyberattacks, particularly in multi-cloud environments. The results provide practical guidance for organizations to design robust cloud security frameworks that balance security, performance, and cost, while supporting innovation and regulatory compliance.</p>