PLINQ is a part of the .NET Framework. It stands for Parallel LINQ. This is a type of LINQ to Objects that executes in multiple threads to perform queries. A query is broken up by PLINQ, executed independently in parallel, with the results being merged together at the end. The act of dividing the query into parallel parts is called Partitioning in PLINQ.

The PLINQ implementation support different types of aggregation such as sum or average. It can also perform sorting in parallel. Anything available in LINQ to Objects is supported in PLINQ. However that does not mean all operators gain performance due to the parallelization.