[//]: # (title: Program Structure Interface \(PSI\))

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The Program Structure Interface, commonly referred to as just PSI, is the layer in the _IntelliJ Platform_ responsible for parsing files and creating the syntactic and semantic code model that powers so many of the platform's features.

* [PSI Files](psi_files.md)
* [File View Providers](file_view_providers.md)
* [PSI Elements](psi_elements.md)

 >  A useful tool for debugging the PSI implementation is the [PsiViewer plugin](https://plugins.jetbrains.com/plugin/227-psiviewer).
> It can show you the PSI tree structure, the properties of every PSI element, and highlight its text range.