Multitenancy is a concept in which a single instance of a software application or service serves multiple customers or "tenants." Each tenant has their own isolated environment, separate from other tenants, and is only able to access and modify their own data.

In simple words, it means that a single software application or service can be used by multiple customers or organizations, each with their own unique data and settings. This allows for more efficient use of resources and can save costs compared to having each tenant run their own separate instance of the software.

An example of multitenancy is a cloud-based software application that is used by multiple companies. Each company has their own account and can only access and modify their own data, but they all use the same software application. Another example is a monitoring system that is used by multiple teams within an organization, each team can only access and see their own metrics and alerts, but they all use the same system.

Multitenancy allows for efficient resource utilization and cost savings, but can also bring some challenges like isolation, security, and performance. It is important to consider these challenges when designing a multitenant system.