# Models

Source: https://pianistpy.com/docs/guide/models

A model (`Model`) is an equilibrium of one or more components, untruncated or truncated in phase
space. Each component is a density profile with a velocity anisotropy, and the model holds the distribution
function of each component. A model is built in the four main steps below.

- [Density profiles (DoublePowerLaw)](https://pianistpy.com/docs/guide/profiles)

- [Velocity anisotropy (Anisotropy, Component)](https://pianistpy.com/docs/guide/anisotropy)

- [Distribution functions (compute_df)](https://pianistpy.com/docs/guide/df)

- [Truncation in phase space (truncate, solve)](https://pianistpy.com/docs/guide/truncation)