diff --git a/calsocial/__init__.py b/calsocial/__init__.py
index 760bd30..b8db121 100644
--- a/calsocial/__init__.py
+++ b/calsocial/__init__.py
@@ -14,6 +14,9 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+"""Main module for the Calendar.social app
+"""
+
 from datetime import datetime
 from functools import wraps
 import os
@@ -40,6 +43,9 @@ def get_locale():
 
 
 def template_vars():
+    """Function to inject global template variables
+    """
+
     now = datetime.utcnow()
 
     return {
@@ -50,6 +56,12 @@ def template_vars():
 
 
 def route(*args, **kwargs):
+    """Mark a function as a future route
+
+    Such functions will be iterated over when the application is initialised.  ``*args`` and
+    ``**kwargs`` will be passed verbatim to `Flask.route()`.
+    """
+
     def decorator(func):
         setattr(func, 'routing', (args, kwargs))
 
@@ -59,6 +71,9 @@ def route(*args, **kwargs):
 
 
 class CalendarSocialApp(Flask):
+    """The Calendar.social app
+    """
+
     def __init__(self, name, config=None):
         from .models import db, User, Role
         from .security import security
@@ -93,6 +108,12 @@ class CalendarSocialApp(Flask):
 
     @route('/')
     def hello(self):
+        """View for the main page
+
+        This will display a welcome message for users not logged in; for others, their main
+        calendar view is displayed.
+        """
+
         from .calendar_system.gregorian import GregorianCalendar
 
         if not current_user.is_authenticated:
@@ -109,6 +130,12 @@ class CalendarSocialApp(Flask):
 
     @route('/register', methods=['POST', 'GET'])
     def register(self):
+        """View for user registration
+
+        If the ``REGISTRATION_FAILED`` configuration value is set to ``True`` it displays the
+        registration disabled template.  Otherwise, it performs user registration.
+        """
+
         if not current_app.config['REGISTRATION_ENABLED']:
             return render_template('registration-disabled.html')
 
@@ -132,6 +159,11 @@ class CalendarSocialApp(Flask):
     @route('/new-event', methods=['GET', 'POST'])
     @login_required
     def new_event(self):
+        """View for creating a new event
+
+        This presents a form to the user that allows entering event details.
+        """
+
         from .forms import EventForm
         from .models import db, Event
 
diff --git a/calsocial/__main__.py b/calsocial/__main__.py
index 0206b89..26c561c 100644
--- a/calsocial/__main__.py
+++ b/calsocial/__main__.py
@@ -1,3 +1,6 @@
+"""Main module for Calendar.social so the app can be run directly.
+"""
+
 from calsocial import CalendarSocialApp
 
 
diff --git a/calsocial/calendar_system/__init__.py b/calsocial/calendar_system/__init__.py
index a5dda87..dba786f 100644
--- a/calsocial/calendar_system/__init__.py
+++ b/calsocial/calendar_system/__init__.py
@@ -1,15 +1,48 @@
+# Calendar.social
+# Copyright (C) 2018 Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Calendar system base definition for Calendar.social
+"""
+
 class CalendarSystem:
+    """Base class for calendar systems
+    """
+
     __has_months__ = False
     __has_weeks__ = False
 
     @property
     def day_names(self):
+        """An iterable of day names
+        """
+
         raise NotImplementedError()
 
     @property
     def month(self):
+        """The name of the current month, if applicable
+
+        It may include the year.
+        """
+
         raise NotImplementedError()
 
     @property
     def days(self):
+        """An iterable of days to be displayed on the month view, if applicable
+        """
+
         raise NotImplementedError()
diff --git a/calsocial/calendar_system/gregorian.py b/calsocial/calendar_system/gregorian.py
index 1113761..0705269 100644
--- a/calsocial/calendar_system/gregorian.py
+++ b/calsocial/calendar_system/gregorian.py
@@ -1,3 +1,22 @@
+# Calendar.social
+# Copyright (C) 2018 Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Gregorian calendar system for Calendar.social
+"""
+
 from datetime import datetime, timedelta
 from functools import wraps
 
@@ -7,6 +26,9 @@ from . import CalendarSystem
 
 
 def to_timestamp(func):
+    """Decorator that converts the return value of a function from `datetime` to a UNIX timestamp
+    """
+
     @wraps(func)
     def decorator(*args, **kwargs):
         return func(*args, **kwargs).timestamp()
@@ -15,6 +37,9 @@ def to_timestamp(func):
 
 
 class GregorianCalendar(CalendarSystem):
+    """Gregorian calendar system for Calendar.social
+    """
+
     __name__ = _('Gregorian')
 
     __has_months__ = True
@@ -75,15 +100,24 @@ class GregorianCalendar(CalendarSystem):
     @property
     @to_timestamp
     def prev_year(self):
+        """Returns the timestamp of the same date in the previous year
+        """
+
         return self.timestamp.replace(year=self.timestamp.year - 1)
 
     @property
     def prev_year_year(self):
+        """The number of the previous year
+        """
+
         return self.timestamp.replace(year=self.timestamp.year - 1).year
 
     @property
     @to_timestamp
     def prev_month(self):
+        """Returns the timestamp of the same day in the previous month
+        """
+
         if self.timestamp.month == 1:
             return self.prev_year.replace(month=12)
 
@@ -91,6 +125,9 @@ class GregorianCalendar(CalendarSystem):
 
     @property
     def prev_month_name(self):
+        """The name of the previous month
+        """
+
         if self.timestamp.month == 1:
             timestamp = self.prev_year.replace(month=12)
         else:
@@ -101,6 +138,9 @@ class GregorianCalendar(CalendarSystem):
     @property
     @to_timestamp
     def next_month(self):
+        """Returns the timestamp of the same day in the next month
+        """
+
         if self.timestamp.month == 12:
             return self.next_year.replace(month=1)
 
@@ -108,6 +148,9 @@ class GregorianCalendar(CalendarSystem):
 
     @property
     def next_month_name(self):
+        """The name of the next month
+        """
+
         if self.timestamp.month == 12:
             timestamp = self.prev_year.replace(month=1)
         else:
@@ -118,14 +161,23 @@ class GregorianCalendar(CalendarSystem):
     @property
     @to_timestamp
     def next_year(self):
+        """Returns the timestamp of the same date in the next year
+        """
+
         return self.timestamp.replace(year=self.timestamp.year + 1)
 
     @property
     def next_year_year(self):
+        """The number of the next year
+        """
+
         return self.timestamp.replace(year=self.timestamp.year + 1).year
 
     @property
     def has_today(self):
+        """``True`` if the set month holds today’s date
+        """
+
         now = datetime.utcnow()
         month_start_timestamp = self.timestamp.replace(day=1,
                                                        hour=0,
@@ -144,6 +196,9 @@ class GregorianCalendar(CalendarSystem):
 
     @staticmethod
     def day_events(date, user=None):
+        """Returns all events for a given day
+        """
+
         from ..models import Event
 
         events = Event.query
diff --git a/calsocial/config_dev.py b/calsocial/config_dev.py
index 51f0fff..5cc4d10 100644
--- a/calsocial/config_dev.py
+++ b/calsocial/config_dev.py
@@ -1,5 +1,9 @@
+"""Configuration file for the development environment
+"""
+
 DEBUG = True
 ENV = 'dev'
+#: If ``True``, registration on the site is enabled.
 REGISTRATION_ENABLED = True
 
 SQLALCHEMY_DATABASE_URI = 'sqlite:///local.db'
diff --git a/calsocial/forms.py b/calsocial/forms.py
index dad0bd9..a5973eb 100644
--- a/calsocial/forms.py
+++ b/calsocial/forms.py
@@ -1,3 +1,22 @@
+# Calendar.social
+# Copyright (C) 2018 Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Forms for Calendar.social
+"""
+
 from flask_babelex import lazy_gettext as _
 from flask_wtf import FlaskForm
 import pytz
@@ -8,17 +27,32 @@ from wtforms.widgets import TextArea
 
 
 class RegistrationForm(FlaskForm):
+    """Registration form
+    """
+
     username = StringField(_('Username'), validators=[DataRequired()])
     email = StringField(_('Email address'), validators=[Email()])
     password = PasswordField(_('Password'), validators=[DataRequired()])
     password_retype = PasswordField(_('Password, once more'), validators=[DataRequired()])
 
     def validate_password_retype(self, field):
+        """Validate the ``password_retype`` field
+
+        Its value must match the ``password`` field’s.
+        """
+
         if field.data != self.password.data:
             raise ValidationError(_('The two passwords must match!'))
 
 
 class TimezoneField(SelectField):
+    """Field for selecting a time zone
+
+    Note: this field overrides whatever is passed to the ``choices`` parameter, and fills
+    ``choices`` with the common timezones of pytz.  In every other aspects, it behaves exactly
+    like `SelectField`.
+    """
+
     def __init__(self, *args, **kwargs):
         kwargs.update({
             'choices': [
@@ -44,6 +78,9 @@ class TimezoneField(SelectField):
 
     @staticmethod
     def is_pytz_instance(value):
+        """Check if ``value`` is a valid pytz time zone instance
+        """
+
         return value is pytz.UTC or isinstance(value, pytz.tzinfo.BaseTzInfo)
 
     def process_data(self, value):
@@ -68,6 +105,9 @@ class TimezoneField(SelectField):
 
 
 class EventForm(FlaskForm):
+    """Form for event creation/editing
+    """
+
     title = StringField(_('Title'), validators=[DataRequired()])
     time_zone = TimezoneField(_('Time zone'), validators=[DataRequired()])
     start_time = DateTimeField(_('Start time'), validators=[DataRequired()])
@@ -76,6 +116,9 @@ class EventForm(FlaskForm):
     description = StringField(_('Description'), widget=TextArea())
 
     def populate_obj(self, obj):
+        """Populate ``obj`` with event data
+        """
+
         FlaskForm.populate_obj(self, obj)
 
         timezone = self.time_zone.data
@@ -85,5 +128,10 @@ class EventForm(FlaskForm):
         obj.end_time = timezone.localize(self.end_time.data).astimezone(pytz.utc)
 
     def validate_end_time(self, field):
+        """Validate the ``end_time`` field
+
+        Its value must be later than the value of the ``start_time`` field.
+        """
+
         if field.data < self.start_time.data:
             raise ValidationError(_('End time must be later than start time!'))
diff --git a/calsocial/models.py b/calsocial/models.py
index da48af9..3a813e9 100644
--- a/calsocial/models.py
+++ b/calsocial/models.py
@@ -1,3 +1,22 @@
+# Calendar.social
+# Copyright (C) 2018 Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Database models for Calendar.social
+"""
+
 from datetime import datetime
 
 from flask_security import UserMixin, RoleMixin
@@ -11,6 +30,9 @@ users_roles = db.Table(
 
 
 class User(db.Model, UserMixin):
+    """Database model for users
+    """
+
     __tablename__ = 'users'
     id = db.Column(db.Integer(), primary_key=True)
 
@@ -42,6 +64,9 @@ class User(db.Model, UserMixin):
 
 
 class Role(db.Model, RoleMixin):
+    """Database model for roles
+    """
+
     __tablename__ = 'roles'
     id = db.Column(db.Integer(), primary_key=True)
 
@@ -56,6 +81,9 @@ class Role(db.Model, RoleMixin):
 
 
 class Event(db.Model):
+    """Database model for events
+    """
+
     __tablename__ = 'events'
     id = db.Column(db.Integer(), primary_key=True)
 
@@ -70,10 +98,10 @@ class Event(db.Model):
     #: The time zone to be used for `start_time` and `end_time`
     time_zone = db.Column(db.String(length=80), nullable=False)
 
-    #: The starting timestamp of the event
+    #: The starting timestamp of the event.  It is in the UTC time zone
     start_time = db.Column(db.DateTime(), nullable=False)
 
-    #: The ending timestamp of the event
+    #: The ending timestamp of the event.  It is in the UTC time zone
     end_time = db.Column(db.DateTime(), nullable=False)
 
     #: If `True`, the event is a whole-day event
@@ -89,10 +117,16 @@ class Event(db.Model):
 
     @property
     def start_time_tz(self):
+        """The same timestamp as `start_time`, but in the time zone specified by `time_zone`.
+        """
+
         return self.__as_tz(self.start_time)
 
     @property
     def end_time_tz(self):
+        """The same timestamp as `end_time`, but in the time zone specified by `time_zone`.
+        """
+
         return self.__as_tz(self.end_time)
 
     def __repr__(self):
diff --git a/calsocial/security.py b/calsocial/security.py
index 56ff78e..39bd35b 100644
--- a/calsocial/security.py
+++ b/calsocial/security.py
@@ -1,3 +1,22 @@
+# Calendar.social
+# Copyright (C) 2018 Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Security related things for Calendar.social
+"""
+
 from flask_security import Security
 
 security = Security()