LINQ is a feature of the programming languages C# 3.0 and Visual Basic .NET
LINQ adds, to each of the languages, a SQL-like syntax and vocabulary for querying data sources.
LINQ to Sharepoint allows developers to use SQL-like syntax to query Lists and Libraries in Sharepoint.
LINQ to Sharepoint internally converts the LINQ query to a CAML query to fetch records
Advantage : Strongly typed access to the entities of the list.
Disadvantage : If the new columns are added or its datatype
changed, the datacontext class used by LINQ is no longer valid and may break the code