“Multi-tenancy is an architecture in which a single instance of a software application serves multiple customers. Each customer is called a tenant. Tenants may be given the ability to customize some parts of the application, such as color of the user interface ( UI) or business rules, but they cannot customize the application’s code.”
WhatIs.com.
Multi-tenancy is becoming an increasingly important concept for OSS in the world of XaaS, giving more flexible business models. It allows CSPs to offer advanced self-service and management to wholesalers. It allows different solution integrators or operators to set up different skins and business rules for different customers. It also allows for OSSaaS (OSS as a Service) to be offered to customers on their networks.