diff --git a/cast/filters.py b/cast/filters.py
index 46b687af..cde76c33 100644
--- a/cast/filters.py
+++ b/cast/filters.py
@@ -304,6 +304,16 @@ def set_facet_counts(self, queryset: models.QuerySet) -> None:
 
 
 class PostFilterset(django_filters.FilterSet):
+    """
+    A filterset for posts. It is used to filter the posts faceted navigation
+    style. The filterset facets are configured via the CAST_FILTERSET_FACETS setting.
+
+    The main reason why this code is confusing is that the facets are used
+    as the choices for the filterset fields. But the facets are only available
+    if the queryset is filtered. So the choices of the fields need to be set
+    after the queryset is filtered.
+    """
+
     search = django_filters.CharFilter(field_name="search", method="fulltext_search", label="Search")
     date = django_filters.DateFromToRangeFilter(
         field_name="visible_date",