Language INtegrated Query (LINQ) is the language that we use with Entity Framework to construct and execute queries against a database. A query is a statement that retrieves data from one or more tables. LINQ has many query implementations. At the most basic level, .NET includes LINQ in an object's functionality that allows you to query in-memory collections. LINQ to entities is typically the name that is used when talking about LINQ in relation to Entity Framework. This technology uses Entity Framework in conjunction with a provider for a specific RDBMS to convert LINQ statements to SQL queries. Entity Framework takes care of materialization; the process of converting the results of SQL queries into collections of .NET objects or individual objects.

When you use LINQ to entities queries, you will find out that the SQL is executed against the database when you enumerate the query results. Entity Framework converts LINQ queries to expression trees and then command trees...