diff --git a/src/filecheck.py b/src/filecheck.py
index 36631b1..27cd9ae 100644
--- a/src/filecheck.py
+++ b/src/filecheck.py
@@ -1,3 +1,5 @@
+# check that a file is creatable/writable/editable
+
 import os.path
 
 # check that a file can be edited
diff --git a/src/lattice.py b/src/lattice.py
index fbe5bb7..39d4bef 100644
--- a/src/lattice.py
+++ b/src/lattice.py
@@ -1,3 +1,5 @@
+# define background lattices
+
 from point import Point
 
 # parent class of all lattices
diff --git a/src/painter.py b/src/painter.py
index 8a48706..ee922ae 100644
--- a/src/painter.py
+++ b/src/painter.py
@@ -1,3 +1,5 @@
+# main drawing class
+
 import sys
 import math
 from kivy.uix.widget import Widget
diff --git a/src/point.py b/src/point.py
index eaf8dd6..b67d4ed 100644
--- a/src/point.py
+++ b/src/point.py
@@ -1,3 +1,5 @@
+# two-dimensional point structure
+
 import math
 
 # point in two dimensions