# Chapter 3 UI

### Table of contents

* [Part 1 — While True Script \[It's all what you need\]](https://developer.supervisely.com/app-development/advanced/in-depth-app-development/chapter-3-ui/part-1-while-true-script-its-all-what-you-need)
* [Part 2 — UI Rendering \[Simplest UI Application\]](https://developer.supervisely.com/app-development/advanced/in-depth-app-development/chapter-3-ui/part-2-ui-rendering-simplest-ui-application)
* [Part 3 — APP Handlers \[Handle Events and Errors\]](https://developer.supervisely.com/app-development/advanced/in-depth-app-development/chapter-3-ui/part-3-app-handlers-handle-events-and-errors)
* [Part 4 — State and Data \[Mutable Fields\]](https://developer.supervisely.com/app-development/advanced/in-depth-app-development/chapter-3-ui/part-4-state-and-data-mutable-fields)
* [Part 5 — Styling your app \[Customizing the UI\]](https://developer.supervisely.com/app-development/advanced/in-depth-app-development/chapter-3-ui/part-5-styling-your-app-customizing-the-ui)