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

# Segments and segmentations

Dimensions divide a model into useful groups. Two related terms describe that structure.

## Segmentation

A **segmentation** is the dimension, or combination of dimensions, used to break down a value.

Examples:

* Revenue by Department
* Revenue by Region
* Revenue by Department and Region

In the first example, Department is the segmentation.

## Segment

A **segment** is one specific position inside a segmentation.

Examples:

* Department = Sales
* Region = West
* Department = Sales and Region = West

## Why the distinction matters

A segmentation formula applies to a way of breaking down the model. A segment formula applies only to one or more specific dimension values.

For example:

* A Department segmentation formula can calculate Revenue for every department.
* A Sales segment formula can override that calculation only for Sales.
* The broader formula continues to apply to Engineering, Marketing, and other departments.

## Date is also a dimension

When a formula is calculated by month, quarter, or year, Date is part of its segmentation. This matters when a formula uses a Formula period such as Actuals or Forecast.

## Keep scope as broad as possible

Start with a default formula. Add segmentation or segment formulas only when the calculation genuinely needs to differ. This makes the model easier to understand and maintain.