diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index c5387eb99606cb700c5a3cc4f1c429fe120a7b7e..fae955f8158ad619db4bae1662abd226d6312339 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -132,6 +132,11 @@ def preloaders_for_hash(association, records, scope)
         }
       end
 
+      # Loads all the given data into +records+ for a singular +association+.
+      #
+      # Functions by instantiating a preloader class such as Preloader::HasManyThrough and
+      # call the +run+ method for each passed in class in the +records+ argument.
+      #
       # Not all records have the same class, so group then preload group on the reflection
       # itself so that if various subclass share the same association then we do not split
       # them unnecessarily