diff --git a/lib/vox/data.ex b/lib/vox/data.ex
index 96e3d57..9fb8393 100644
--- a/lib/vox/data.ex
+++ b/lib/vox/data.ex
@@ -1,15 +1,27 @@
 defprotocol Vox.Data do
+    @moduledoc """
+      Generic interface for voxel data.
+    """
     @type no_impl :: nil
 
     @type face :: :left | :right | :bottom | :top | :front | :back
     @type origin :: { face, face, face }
 
+    @doc """
+      Gets the orientation of the coordinate system the voxel data uses.
+    """
     @spec origin(t) :: origin
     def origin(data)
 
+    @doc """
+      Gets all the models represented by the voxel data
+    """
     @spec models(t) :: [Vox.Model.t]
     def models(data)
 
+    @doc """
+      Get the implementation for any optional functions.
+    """
     @spec impl(t, :model) :: ((t, Vox.Model.id) -> Vox.Model.t | nil) | no_impl
     @spec impl(t, :model_count) :: (t -> non_neg_integer) | no_impl
     @spec impl(t, :voxel) :: ((t, Vox.Model.id, Vox.Model.axis, Vox.Model.axis, Vox.Model.axis) -> { :ok, Vox.Voxel.t | nil } | Vox.Model.error(Vox.Model.bounds_error | Vox.Model.unknown_error)) | no_impl