> For the complete documentation index, see [llms.txt](https://docs.iotmp.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.iotmp.io/iotmp/message-structure.md).

# Message Structure

IOTMP communication is based on the exchange of structured messages between clients and servers. Each IOT **message** is composed of two main parts:

1. **Header** – mandatory, contains metadata about the message type and the size of its payload.
2. **Body (Payload)** – optional, contains the actual data being transmitted.

The general structure is:

|                                      Message Structure                                      |
| :-----------------------------------------------------------------------------------------: |
| [Message Header](/iotmp/message-structure/message-header.md), present in all IOTMP messages |
|   [Message Body](/iotmp/message-structure/message-body.md), present in some IOTMP messages  |