> 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/basics-and-essentials/what-is-a-data-type.md).

# What is a Data type?

* A Data Type is a categorization of data. A Data Type in a variable defines how the variable's value will be interpreted and processed.
* Simple data types are String, Boolean, Integer, Numerical, Character, GUID, Timestamp, and DateTime.

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* Complex data types are API gateway, Json, JXPFlowAppActivity, JXPHttpRestResponse, JXPResponse, Record, WebRequest, and WebResponse.&#x20;

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* Entity-based data types are user-defined entities.

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* A variable can contain only one (1) Data Type.