Microsoft Entity Framework enables developers to quickly produce code interacting with relational data stores, without having to resort to SQL or use of proprietary intermediate layers. Plain C# objects can automatically be converted to tables, and their retrieval code written in the same language. Entity Framework not only saves development time, but also helps reduce costs of data access code maintenance and developers communications.
Such large projects as Dynamics CRM and Sharepoint make use of Entity Framework in their data access code. It is impossible to tell just how many applications out there have Entity Framework in their arsenal, but it is safe to say that these days it is the default choice for C# developers everywhere.