Lambda expressions reduce the amount of work needed when iterating through data.  All enumerable data is queryable through LINQ through the use of a SQL-like query (what I mean by that is the query looks like SQL, but is a different flavor). LINQ has an in-built mechanism to loop through enumerable data and use certain conditions setup in the where clauses to filter the data.  LINQ queries are quite effective in what they do.

Lambda expressions work in a similar way. Some of the existing extension methods feature built-in lamdba expressions to perform certain actions and to make it easier to perform repetitive work.  We shall see this soon.  Lambda expressions do not require extension methods to work, but this is the most common usage currently.