# Overview

All the show programming that relates to timelines, layers and content sequencing happes in ***Timelines*** and ***Timeline Editor*** windows.

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In the **Timelines** window you can control and monitor Play state of all the Timelines and Timeline groups.

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In the **Timeline Editor** window, you can edit *Sections, Layers,* and *Markers* of a given *Timeline*.

## Hierarchy

Timelines and Timeline Groups in LightAct are organized in a hierarchical way.

* **Timeline Group** can contain one or several Timelines.
* **Timeline** can contain several layers, sections or markers. A Timeline can be only in one Timeline Group.
* **Sections, layers and markers** are elements within one Timeline.

## Play controls

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Every Timeline and Timeline group has its own set of play controls.

* **Play**: this play states means the playhead will continue advancing from left to right even over section borders.
* **Play and pause**: playhead will advance to the last frame of its section, then pause (hold).
* **Play and loop**: playhead will advance to the last frame of its section, then jump back to the first frame of that section.
* **Pause**: playhead doesn't advance, but the active layers are still executing.
* **Stop**: playhead doesn't advance. No layers are executing.
* **Jump to previous**: executes a jump to the previous section, marker or layer.
* **Jump to next**: executes a jump to the next section, marker or layer.

## Timeline group Mode

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Every Timeline group has a Mode property with 2 options:

1. **Only one**: this mode means that only one Timeline in this group can be in a Play state at the same time. If another Timeline switches to a Play state, all the other will switch to Pause.
2. **Multiple**: this mode means that the play states of Timelines in this group are completely independent.

{% hint style="info" %}
**Good to know**: Only one mode is particularly useful with Timeline cross-fades.
{% endhint %}

## Speed multiplier

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In LightAct 4.12 we've introduced **Speed multiplier**. This affects the playback speed of the entire timeline.