Getting Started

The basic units of data in LINQ are sequences and elements. A sequence is any object that implements IEnumerable<T> and an element is each item in the sequence. In the following example, names is a sequence, and "Tom", "Dick", and "Harry" are elements:

string[] names = { "Tom", "Dick", "Harry" };

We call this a local sequence because it represents a local collection of objects in memory.

A query operator is a method that transforms a sequence. A typical query operator accepts an input sequence and emits a transformed output sequence. In the Enumerable class in System.Linq, there are around 40 query operators—all implemented as static extension methods. These are called standard query operators.