What is Data Driven Subscription in SSRS

A Data Driven Subscription is dynamically retrieves subscription data from an external data source at a runtime. You can also specify some static values  and default values that you can specify when you define the subscription. A Data Driven. Subscription is especially use full in the following scenarios.

• Your list of subscribers is not fixed and changed often.
• You need to filter the data based on different parameters for each user, and you need to retrieve these parameters at runtime.
• You need to use different rendering formats and delivery methods for different users, or you have to vary formats and methods for each execution