ORM—Object-Relational Mapping

LINQ to Entities is considered to be one of Microsoft's new ORM products. So before we start explaining LINQ to Entities let us first understand what ORM is.

ORM stands for Object-Relational Mapping. Sometimes it is called O/RM or O/R mapping. It is a programming technique that contains a set of classes that map relational database entities to objects in a specific programming language.

Initially applications could call specified, native database APIs to communicate with a database. For example, Oracle Pro*C is a set of APIs supplied by Oracle to query, insert, update, or delete records in an Oracle database from C applications. The Pro*C pre-compiler translates embedded SQL into calls to the Oracle runtime library (SQLLIB).

Then ODBC (Open Database Connectivity) was developed to unify all of the communication protocols for various RDBMS. ODBC was designed to be independent of programming languages, database systems, and operating systems. So with ODBC, one application...