Linq – InternetException

consistent model for working with data from various kinds of sources and formats (XML, SQL, ADO.NET, Datasets, .NET collections etc)
3 stages of working with LINQ:
- obtain data source
- create the query
- execute the query
data sources implements IEnumerable<> and are called queryable types
IQueryable<> interface inherits from IEnumerable<>
generally it is better to use LINQ via IQueryable<> which produces deferred query instead of producing result immediately
queries can be executed multiple times
queries can be forced immediate execution via Count(), Max(), ToList() or ToArray() etc.
LINQ to DB libraries (like EntityFramework) usually are implemented via Expression Trees