> For the complete documentation index, see [llms.txt](https://docs.lenses.io/latest/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lenses.io/latest/user-guide/6.2-user-guide/using/tutorials/sql-studio/accessing-headers.md).

# Accessing headers

This page describes a tutorial for access headers via SQL Studio.

Since version 0.11, Apache Kafka supports message headers. Headers are a typical concept in messaging systems like JMS and transport systems like TCP or HTTP.

They can be used for routing, filtering, and annotation. The header can contain pairs of `key=value`, where the `key` is always a string(text), and the `value` is an array of bytes.

Given that the actual value is an array of bytes, the developer who produces the messages knows whether this array of bytes represents a string, an int, a long, or a double. Lenses can visualize and use the record headers via SQL queries.

By default, Lenses fetches the headers of messages and displays them on the UI.

To view the value of a specific header you can run:

```sql
SELECT HEADERASSTRING("User") as user
FROM trips
LIMIT 100
```


---

# Agent Instructions
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## Querying This Documentation
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```

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