diff --git a/plot_counter.py b/plot_counter.py
index 6732ed9..e527bee 100755
--- a/plot_counter.py
+++ b/plot_counter.py
@@ -1,4 +1,29 @@
 #!/usr/bin/env python3
+""" Plot user counts for different matrix channels
+
+Help is available with the "--help" option.
+
+This program is free software: you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+
+__author__ = "Frank Löffler"
+__contact__ = "frank.loeffler@uni-jena.de"
+__copyright__ = "Copyright 2024, Frank Löffler; 2024 Friedrich-Schiller-Universität Jena"
+__date__ = "2024-03-05"
+__email__ = "frank.loeffler@uni-jena.de"
+__license__ = "AGPLv3"
+__maintainer__ = "frank.loeffler@uni-jena.de"
+__status__ = "Development"
+__version__ = "0.0.1"
+
 import sys, os
 from pprint import pprint
 import argparse
@@ -10,10 +35,11 @@
 
 parser = argparse.ArgumentParser(description="")
 parser.add_argument('file',
-                    help='input json file to use')
+                    help='input json file to use. The output of the matrixcounter.py script '
+                         'is the intended input.')
 parser.add_argument('-o', '--output',
                     help='output file to write the figure to; extension defines format to the'
-                         'extend matplotlib supports')
+                         'extend matplotlib supports; default: counter_matrix.pdf')
 args = vars(parser.parse_args())
 
 try:
@@ -34,26 +60,33 @@
 xmin=datetime.fromisoformat('2999-01-01T00:00:00')
 xmax=datetime.fromisoformat('1999-01-01T00:00:00')
 
+# go through all rooms and sort by current (last) user count
 for room, roomdata in sorted(data['rooms'].items(), key=lambda x: x[1]['counts'][1][-1]):
+    # exclude a few rooms; TODO: already do not include those numbers in the collected data
     if roomdata['name'].startswith('deRSE-test'):
         continue
     if roomdata['name'].startswith('deRSE-alt'):
         continue
     if roomdata['name'].startswith('de-RSE-alt'):
         continue
+    # convert data to the right types for plotting
     times  = [datetime.fromisoformat(s) for s in roomdata['counts'][0]]
     counts = roomdata['counts'][1]
+    # add one more "fake" datapoint, as stairs() requires len(edges) = len(data)+1
     times.append(times[-1])
+    # get global extrema as limits later
     xmin = min(xmin, times[0])
     xmax = max(xmax, times[-1])
-
+    # the actual plot line
     ax.stairs(counts, edges=times, lw=2, label=roomdata['name'])
 
-ax.spines['top'].set_visible(False)
-ax.spines['left'].set_visible(False)
-
+# limit to the observed time range and ensure ymin to be 0
 ax.set_xlim(xmin=xmin, xmax=xmax)
 ax.set_ylim(ymin=0)
+
+# some plot cosmetics
+ax.spines['top'].set_visible(False)
+ax.spines['left'].set_visible(False)
 ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m-%d'))
 for label in ax.get_xticklabels(which='major'):
     label.set(rotation=20, horizontalalignment='right')