1) Salesforce.com's multitenant architecture allows multiple customers to use the same application instance running on the same server infrastructure, lowering costs while maintaining performance and security.
2) All customer data and configurations are stored separately in the same database using unique customer IDs to isolate each tenant's data.
3) This approach provides significant benefits including automatic upgrades, high performance at scale through query optimization, and faster innovation since all customers use the same codebase.