> ## Documentation Index
> Fetch the complete documentation index at: https://enterprise-docs.dify.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Orchestration Logic

> How to arrange, nest, or reuse nodes when building a Workflow or Chatflow

## Serial and Parallel Execution

<Frame>
  <img src="https://mintcdn.com/dify-enterprise-docs/zvhvyUvEpyoIONBf/images/use-dify/workflow/serial-vs-parallel-execution.png?fit=max&auto=format&n=zvhvyUvEpyoIONBf&q=85&s=cca6e70c8635e03a3b970bd5b53162a4" alt="Serial vs. Parallel Execution" width="1896" height="568" data-path="images/use-dify/workflow/serial-vs-parallel-execution.png" />
</Frame>

When building a workflow, you can arrange nodes in series or in parallel:

* **In series**, nodes run one after another. Each node can read variables from any node earlier in the chain.

* **In parallel**, nodes run at the same time. They can't read each other's variables, but where parallel branches converge, the downstream node can read from all of them.

<Info>
  A single execution path supports up to 50 nodes.
</Info>

## Node Reuse

All nodes except Start can be copied and pasted within the same workflow. When you paste a node, its configuration moves with it.

## Iteration

For nodes that should run multiple times (once per item in a list), place them inside an [Iteration](/en/2.8.x/use/nodes/iteration) node.