DataAccessException is a subclass of RuntimeException that provides an API for dealing with recoverable exceptions that occur during Data Access operations. In particular, this exception is thrown when errors related to retrieving data from databases occur, such as errors in connection or query execution. It's important to understand that DataAccessException marks the boundary of the app's codebase and the data access layers such as JDBC, Hibernate, JPA and others such that it still allows for meaningful explanation of underlying exceptions without introducing implementation-specific details into the application layer. Furthermore, DataAccessExceptions provide methods for retrieving certain vendor-specific codes or SQL state codes which can help developers to determine and fix the root cause of the error more quickly. Ultimately, understanding how to configure and use DataAccessExceptions are essential skills for any Java developer who plans on developing projects using Spring MVC Framework.  By being familiar with how they work in practice, developers can save time debugging their applications while also taking advantage of rich diagnostic tools provided by Spring MVC Framework.