The LINQ has a 3 layered Architecture. In the upper layer consists of the language extensions and the bottom layer consists of data sources that are typically objects implementing IEnumerable<T> or IQueryable<T> generic interfaces.
The LINQ contain some major components,
1. LINQ to Objects.
2. LINQ to ADO.NET, which includes.
3. LINQ to SQL (formerly called DLinq).
4. LINQ to DataSet (formerly called LINQ over DataSet).
5. LINQ to Entities.
6. LINQ to XML (formerly called XLinq).