Multitenancy
Definition
Multitenancy is a software architecture where one instance of the application serves multiple customers. Each customer's data is isolated but shares the same codebase.
Extended Definition
Example: Salesforce runs one massive database and application that serves millions of companies. Each company sees only their data, but all share the same infrastructure. Benefits: lower infrastructure costs, easier updates (deploy once for all customers), better resource utilization. Drawbacks: security complexity, noisy neighbor problems, customization limits. Alternative: single-tenancy (separate instance per customer).