# ESDL concepts This chapter describes the ESDL concept. The following topics will be covered: * [Design principles](https://energytransition.gitbook.io/esdl/esdl-concepts/design-principles): the general design principles behind the language: capabilities and aggregation * [Energy System structure](https://energytransition.gitbook.io/esdl/esdl-concepts/energy-system-structure): the high level structure of an EnergySystem description * [Data types](https://energytransition.gitbook.io/esdl/esdl-concepts/data-types): the most important data types in the language: EnergySystem, Instance, Potential, Area, Asset, EnergyAsset, Port, Profile * [ESDL model](https://energytransition.gitbook.io/esdl/esdl-concepts/esdl-model): a visualization of the ESDL model --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://energytransition.gitbook.io/esdl/esdl-concepts.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.