---
title: Glossary
description: Definitions for terms used across Magic Transit documentation.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/magic-transit/llms.txt  
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# Glossary

Review the definitions for terms used across Cloudflare's Magic Transit documentation.

| Term                 | Definition                                                                                                                                                                                                                                                                                                                                               |
| -------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| letter of agency     | Sometimes referred to as a Letter of Authorization. A document that authorizes Cloudflare to advertise your prefixes. This is required so transit providers can accept the routes Cloudflare advertises on your behalf.                                                                                                                                  |
| policy-based routing | Policy-based routing (PBR) is a technique used to make routing decisions based on policies set by your administrador.                                                                                                                                                                                                                                    |
| prefix               | A number that identifies the network portion of an IP address. It tells devices if an IP address is on the same network or not. It is shown as a number after a slash (for example, /31) at the end of the IP address. Using an analogy, the prefix is like a street address. If an IP is in the same street, it belongs to the same network of devices. |

```json
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```