Multi-tenant SaaS tenancy implies centralized administration to maintain a common code-based application and run a common instance(s) of the application for multiple tenants (organizations/businesses). However, the confidential data for each tenant is secured from any other tenant. Apart from the software application, each customer also shares a multi-tenant database. As for the data, each set of data is tagged as belonging to each customer. The software is pre-programmed to segregate and secure the data for each user.
Multi-tenant SaaS architecture makes for long-term benefits for vendors as well as users, be it in terms of maintenance, cost of investment, or development. However, no matter which architecture you use, it entails a few challenges which you need to identify and take in your stride in the long-run.