# Precompositions
Precompositions (precomps) are self-contained nested scenes that help you organize complex animations, create reusable components, and build hierarchical projects.
## What are precompositions?
A precomposition is a composition nested within another composition.
**Precomp fundamentals:**
**Precomposition Asset** — the actual nested scene (lives in assets)
**Precomposition Layer** — reference to the asset (lives in timeline)
One asset can be used by multiple layers (instances)
**Why use precompositions:**
**Organization:** Break complex scenes into manageable pieces
**Reusability:** Create once, use multiple times
**Isolation:** Animation independent from parent
**Performance:** Organize logically for easier editing
## Creating precompositions
1. Select layers in timeline/outliner
2. Right-click → **Create Scene** (or shift + cmd/ctrl + c)
3. The selected layers are moved into a new precomp
4. A precomposition layer is created at their position
## Precomp properties
**Standard properties:**
Transform (position, rotation, scale, opacity)
Blend mode
Visibility and lock state
Parent (can be parented to other layers)
**Precomp-specific:**
**Precomp Size** — width and height of nested scene
**Bounds Mode** — Scene bounds vs fit to content
**Referenced Asset** — which precomp asset it uses
## Bounds modes
**Scene Bounds (Default):**
Bounding box matches full scene size
Consistent dimensions regardless of content
Transform handles at scene edges
**Fit to Content:**
Bounding box wraps visible content tightly
Bounds adjust if content changes
More efficient for small content in large scene
## Working with multiple precomps
**Reusing precomps:**
1. Create a Precomposition Asset once
2. Add multiple Precomposition Layers referencing it
3. Each instance shares the same content
4. Edit asset updates all instances
**Breaking precompositions:**
1. Select Precomposition Layer
2. Right-click → **Break Scene** (or shift + cmd/ctrl + b)
3. Precomp layers move to parent scene
4. Precomposition Layer is removed
## Precomp timeline
**Independent timeline:**
Each precomp has own timeline duration
Own frame rate (typically matches main scene)
Independent keyframes and animations
Separate work area
**Duration management:**
Define when creating precomp
Matches main scene by default
Can extend or shorten as needed by dragging from its left or right edges
Dark green area shows clipped portion. Light green shows visible duration.