The purpose of multi-tenancy in cloud computing is to allow multiple users or organizations to share the same application resources while keeping their data isolated and secure. This architecture enables cost-effectiveness, as infrastructure and maintenance are managed centrally, reducing operational expenses for individual tenants. Additionally, multi-tenancy promotes greater scalability and resource optimization, as resources can be allocated dynamically based on demand. However, it also necessitates strong security protocols to protect each tenant's data integrity and privacy, ensuring that one tenant's activities do not compromise others.