# Use a KB

Knowledge base content is useful for responding to user utterances that would not be a match to a flow but are common questions or requests for information that you want to support. 

You may choose to create one central flow dedicated to responding with your knowledge base content whenever an utterance is logged as unknown (i.e., unmatched to a flow or assigned variable), or strategically trigger it in others flow with carefully placed *Knowledge base* nodes.

<figure><img src="/files/R2X0tmVuB57BYcrpLj5c" alt=""><figcaption></figcaption></figure>

## Invoke in a flow

* Navigate to *Flows* in the workspace menu > Select a flow or add a new flow
* Add a [*Knowledge base* node](/platform/nlx-platform-guide/flows-and-building-blocks/overview/nodes.md#knowledge-base) to the Canvas > Provide a name for reference locally in the flow
* Assign a *Knowledge base* implemented in the workspace to the node
  * If you have provided [*Metadata*](/platform/nlx-platform-guide/flows-and-building-blocks/knowledge-bases/add-metadata.md) to your *Knowledge base*, you may enter IF comparator statements `=` to provide a filter(s) whenever the node is hit
  * If you want to support citations, follow [setup here](/platform/nlx-platform-guide/flows-and-building-blocks/knowledge-bases/support-citations.md)
* Link a *Basic* node from the *Knowledge base* node's *Match* edge > Enter the placeholder name given and the answer `{"yourKBname".answer}` as a message on the *Basic* node
* Proceed from the *Basic* node to the rest of your flow or redirect to another flow
* Click *Save*

If creating one central flow to handle unknown responses, assign your flow to your application's [*Unknown* default behavior](/platform/nlx-platform-guide/ai-applications/setup.md#default-behavior):

* Navigate to an application in your workspace > Click the application's *Default behavior* tab
* Under *Unknown* behavior, toggle from *Quick replies* to *Flow*
* Select your custom flow where your *Knowledge base* is invoked
* Click *Save*
* Create a new application build and deploy through the application's *Deployment* tab to experience your new knowledge base

{% hint style="warning" %}
User queries that cannot be matched to content in your *Knowledge base* eject out of the *Knowledge base* node's *No match* edge.
{% endhint %}


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.nlx.ai/platform/nlx-platform-guide/flows-and-building-blocks/knowledge-bases/use-a-kb.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.