ADO.NET Entity Framework and Linq to Entities

LINQ to Entities is really simply the standard LINQ extension methods (Where, OrderBy, etc), when used to query Entity Framework. This isn't the only option; EF can also be queried in a custom dialect of SQL - Entity SQL. In reality, the LINQ extension methods are used to generate Entity SQL, and then that Entity SQL is passed down to the provider.

That way, people implementing a new EF provider (since it is extensible) only have to worry about one thing for query: Entity SQL.

Of course, to strictly count as LINQ, you would need to use the language part too, i.e.

from product in db.Products
     where product.IsActive
     select product.Name;

etc - but since this boils down to extension methods anyway (on Queryable/IQueryable<T>), most people would count direct extension usage as LINQ - i.e.

var qry = db.Products.Where(x=>x.IsActive).Select(x=>x.Name);