> ## Documentation Index
> Fetch the complete documentation index at: https://captions.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Effects, Masks, and Appearance

> Change how a selected layer looks: effects, masks, blend mode, and opacity.

Select a layer on the timeline to open its settings. Visual layers (video, image, text, and shape) and effect layers share the same kinds of controls.

## Effects

Add a treatment to the selected layer, such as color, blur, glow, distortion, or texture. An effect on one layer stays on that layer. To treat everything underneath for a stretch of time, add an [effect layer](https://captions.ai/help/web/timeline/effect-layer.md) instead.

## Masks

A mask limits the layer to part of the frame. You can also use a track matte so another layer's alpha or luma defines the visible area. Invert the matte when the hidden and visible regions should swap.

## Appearance

* **Opacity** fades the layer.
* **Blend mode** mixes the layer with whatever is under it.

Keyframe opacity, effects, and masks when the look should change across the clip. See [Animations](https://captions.ai/help/web/layer-settings/animations.md).


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