PLINQ

Parallel LINQ. Enable multiple threads to execute a query.

// Single-threaded:
int[] fibonacciNumbers = numbers
    .Select(number => Fibonacci(number))
    .ToArray();

// Multi-threaded:
int[] fibonacciNumbers = numbers
    .AsParallel()
    .Select(number => Fibonacci(number))
    .OrderBy(number => number) // Parallel execution can cause results to become disordered.
    .ToArray();