# What is a node in n8n? > A node is one step in an n8n workflow, like reading a sheet or sending an email. How nodes and sub-nodes work, with a real AI agent example. Source: https://learn.ynteractive.com/content/glossary/node · Updated 2026-10-01 · Free from Stepthrough (https://learn.ynteractive.com) [n8n and automation](https://learn.ynteractive.com/content/glossary#topic-n8n-and-automation) · [AI glossary](https://learn.ynteractive.com/content/glossary) Updated October 1, 2026 · By [Robert Breen](https://learn.ynteractive.com/content/about) A node is one step in an n8n workflow: a box on the canvas that does a single job, such as starting the workflow, reading a sheet, filtering rows or sending an email. Data flows from node to node along the lines that connect them. ## Why it matters for a small business Thinking in nodes is how you turn a fuzzy chore into something you can build. "Email each tech their jobs" becomes four boxes: when, get the data, skip what doesn't belong, send. Each box can be opened, tested on its own and fixed without touching the others, which makes problems far easier to find than in one long script. Nodes also show you what's possible. If n8n has a node for an app, you pick an operation from a menu instead of learning that app's technical details. And when a node shows a warning, it's telling you something is missing, usually a credential or a required setting, before the workflow ever runs. ## In a real lesson: Build an AI Job Follow-Up Agent for Electricians In the [electrician follow-up agent lesson](https://learn.ynteractive.com/content/electrician-job-follow-up-ai-agent-n8n), you build a follow-up writer for Oak & Wire Electric, the made-up electrical contractor in the lesson. It starts with two ordinary nodes: **On chat message**, then **AI Agent**, added with the **+** on the right edge of the trigger. The AI Agent node is different from most: it has slots underneath for sub-nodes. As soon as you close it, a red warning appears because it has no model. Clicking the **+** under **Chat Model** and choosing **OpenAI Chat Model** clears it. Then **Simple Memory** goes in the **Memory** slot and **Google Sheets Tool** in the **Tool** slot. These sub-nodes don't sit in the main line. They plug into the agent and give it a brain, a memory and something to act with. Every node has its own settings panel. You double-click to open it, set things like **Operation** (here **Append Row**), **Document** (**Job Follow-Ups**) and **Sheet**, then close it with the **×**. The lesson repeats that open, set, close rhythm for every node, and it's the same rhythm in any n8n build. [Try this lesson free](https://learn.ynteractive.com/modules/n8n-ai-agent-electrical) or [read the step-by-step guide](https://learn.ynteractive.com/content/electrician-job-follow-up-ai-agent-n8n). ## Common confusions ### Node vs sub-node A regular node sits in the main flow and passes its output to the next node. A sub-node, such as a chat model, memory or tool, attaches under a parent like the [AI Agent node](https://learn.ynteractive.com/content/glossary/ai-agent-node) and only works through it. ### Gmail node vs Gmail Tool They reach the same app but run differently. A Gmail node in the main flow runs every time data reaches it. A Gmail Tool attached to an agent runs only when the agent decides to use it, which is why the system message has to say when. ## Tips - Rename nodes to say what they do, like "Skip unassigned jobs", so the canvas reads like a checklist. - Test one node on its own before running the whole workflow. Most nodes have their own test button. - Open any node with a warning icon before you run anything. The fix is usually a missing credential or setting. ## Related terms [Workflow](https://learn.ynteractive.com/content/glossary/workflow) · [Trigger](https://learn.ynteractive.com/content/glossary/trigger) · [Action](https://learn.ynteractive.com/content/glossary/action) · [AI Agent node](https://learn.ynteractive.com/content/glossary/ai-agent-node) · [Item (n8n)](https://learn.ynteractive.com/content/glossary/item) · [Tool calling](https://learn.ynteractive.com/content/glossary/tool-calling) ## Where you use it: free lessons - [Build an AI Job Follow-Up Agent for Electricians](https://learn.ynteractive.com/content/electrician-job-follow-up-ai-agent-n8n) (n8n, 12 min) - [n8n AI Agent Tutorial: Save Social Media Ideas to Google Sheets](https://learn.ynteractive.com/content/n8n-ai-agent-tutorial-google-sheets) (n8n, 12 min) - [Daily Job Alerts: Email Each Tech Their Jobs from Google Sheets with n8n](https://learn.ynteractive.com/content/n8n-daily-job-alerts-google-sheets-gmail) (n8n, 10 min) ## Frequently asked questions **How do I find the right node?** Click the + where you want the next step and type the app or the job into the search box, like sheets, gmail or filter. Then pick the specific action from the list. **What does the red warning on an n8n node mean?** Something required is missing. On an AI Agent it usually means no chat model is attached; on an app node it's often a missing credential or setting. [All AI glossary terms, A to Z](https://learn.ynteractive.com/content/glossary) · [Free prompt templates](https://learn.ynteractive.com/content/prompts)