> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-codex-simplify-get-started.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# How ComfyUI works

> Understand templates, workflows, nodes, models, and connections using your first image as an example.

You do not need to build a graph from scratch to use ComfyUI. A template gives you a working starting point. The boxes on its canvas show the steps ComfyUI will take.

<img src="https://mintcdn.com/dripart-codex-simplify-get-started/bBdKmr4zc2lbt060/images/simple_workflow.jpg?fit=max&auto=format&n=bBdKmr4zc2lbt060&q=85&s=6548aa9392fc99719101e1f14e2ff0f0" alt="A simple ComfyUI workflow" width="2400" height="1195" data-path="images/simple_workflow.jpg" />

## Read a workflow from input to result

Imagine the image you made in [Create your first image](/get_started/first_generation):

1. A text input describes what you want.
2. A model is selected or loaded to generate the image.
3. Generation steps use that input and model.
4. An output step shows or saves the finished image.

The boxes are **nodes**. Each node does one job. The lines are **connections**, also called links, that pass results between nodes. You can follow the connections to see where an input goes. You usually edit a prompt or other setting inside a node, then click **Run** to execute the workflow again.

## What is a template?

A **workflow** is the complete set of nodes, settings, and connections. A **template** is a ready-made workflow you can load and edit. A template saves you from assembling the steps yourself, but it does not always include everything needed to run:

* A workflow using a **local model** needs the corresponding model files on your device.
* A workflow using a **Partner Node** calls a hosted model and may need an account and credits.
* A workflow from another person may also need input images or community custom nodes.

A template is therefore a starting point, not a separate way of running ComfyUI. [Compare local and hosted execution](/get_started/where-work-runs).

## What should you change first?

Change one prompt and run the workflow again. Once you can see how the result changes, try one more input, such as image size or an input image. You can leave the rest of the nodes connected as the template provides them.

If a workflow cannot run, [use the symptom-based guide](/get_started/fix-a-workflow). For more detail, see the reference pages for [workflows](/basic-concepts/workflow), [nodes](/basic-concepts/nodes), [models](/basic-concepts/models), and [links](/basic-concepts/links).