> For the complete documentation index, see [llms.txt](https://docs.langstack.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.langstack.com/welcome/get-started/learn-langstack/introduction-to-etl-pipeline/data-formats-in-etl-pipeline.md).

# Data Formats in ETL pipeline

* A data format is how that data is structured; for example, the data format can be a CSV format, Fixed width text format, MySQL table record, or a JSON Format. 
* Depending on the Data Format, other settings may need to be specified for reading and writing data to relevant fields. 
* The Data Format tab consists of three (3) sections: 
  * Reader: This section contains details related to the data source, i.e. where the data is read from. This tab is selected by default. 
  * Writer: This section includes details about the data destination, i.e., where the data is written to. 
  * Field Mapping: This section maps the data fields from the source to the destination.

<figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_9/ch9etldataformtab.png" alt=""><figcaption></figcaption></figure>