Decoding .NET Concurrency: When to Use Threads, Tasks, and Parallelism

Many .NET developers use Thread, Task, async/await, and Parallelism interchangeably without understanding their distinct purposes, resulting in poor performance and unexpected behavior. This comprehensive guide breaks down each concurrency primitive—from low-level Threads to modern Tasks—with clear mental models and practical decision-making criteria. Mastering these concepts is critical for building robust and performant applications.