Definition
Multi-tenancy is a software architecture in which a single application instance serves multiple customers (tenants) with complete data isolation between them. This is the dominant model for SaaSSoftware as a Service - software delivered as subscription service over the internet. products: instead of running one instance per customer (single-tenant), the infrastructure is shared whilst data is kept strictly separate. Tenant isolation is typically implemented via separate databaseOrganised collection of structured information stored and accessed electronically - foundation of all digital systems. schemas, row-level security (RLS) or per-tenant encrypted data keys. Multi-tenant architecture yields lower operational costs, simpler upgrades and better resource utilisation - but requires robust security design to prevent one customer's data being exposed to another. For SaaS in regulated industries such as energy, ISO 27001International standard for information security management systems - provides framework for protecting sensitive information. certification and penetration testing are critical to documenting that tenant isolation holds.