The architecture of Salesforce.com
The architecture of Salesforce.com is multitenant. In a multitenant architecture, a single system serves to the whole consumer base of the provider. This means that the system resources are shared among all the users. Salesforce.com provides a single copy of an app to all the organizations, which runs on Salesforce servers; the organizations are permitted to customize the app according to their business requirements. The resources are similar for all the Salesforce customers. Multiple organizations encounter the same interface to interact with the Salesforce cloud.
Salesforce also applies some limits to the usage termed as governor limits to make sure that a user/organization does not hit the threshold that might affect the system performance, thus making the system work slow or go down for other users or organizations. The clients of Salesforce.com are termed as an organization. Multiple organizations are called tenants, and these tenants further have multiple users based upon the organization's user base or employees.