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See how to build complex designs for your Compose layouts, focusing on layout phase and constraints, subcompose layouts, and intrinsic measurements.  

## Key points

- The*layout phase*is the phase of Compose where element sizing and positioning is defined.
- During the layout phase, each element in the UI tree measures its children, enabling the parent to decide its own size and placing the children in the available 2D space.
- To build a custom layout, call the[`Layout`](https://developer.android.com/reference/kotlin/androidx/compose/ui/layout/package-summary#Layout(kotlin.collections.List,androidx.compose.ui.Modifier,androidx.compose.ui.layout.MultiContentMeasurePolicy))composable, which accepts the composable content as its children.
- Subcomposition enables lazy components to add content on demand while scrolling.
- Subcomposed layouts can have an impact on performance. Use this approach when at least one child's composition depends on the result of another child's measurement.
- Intrinsic measurements let you query children before they're measured.

## Collections that contain this guide

This guide is part of these curated Quick Guide collections that cover broader Android development goals:  
![](https://developer.android.com/static/images/quick-guides/collection-illustration.png)  
![](https://developer.android.com/static/images/picto-icons/collection.svg)  

### Display a list or grid

Lists and grids allow your app to display collections in a visually pleasing form that's easy for users to consume.  
[Quick guide collection](https://developer.android.com/develop/ui/compose/quick-guides/collections/display-a-list-or-grid)
![](https://developer.android.com/static/images/picto-icons/help.svg)  

## Have questions or feedback

Go to our frequently asked questions page and learn about quick guides or reach out and let us know your thoughts.  
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