Final answer:
Source mappings are used to define relationships between fields in various tables, which is essential in maintaining data integrity and consistency across an application.
Step-by-step explanation:
In the context of a lifecycle event within a system or application, source mappings are typically used to define relationships between fields in various tables. Source mappings allow you to link the data in one field of a table to a field in another table, ensuring that the data is consistent and relevant across different parts of the application. These mappings are crucial in database design and application development, as they help maintain data integrity by establishing how data in different tables is related. For example, in a customer relationship management (CRM) system, source mappings would be used to link customer IDs in the customer table with their corresponding orders in the orders table.