diff --git a/config/models.py b/config/models.py
index 1d98ad7..7e9fab4 100644
--- a/config/models.py
+++ b/config/models.py
@@ -14,6 +14,39 @@ Base = declarative_base()
 
 
 class Participant(Base):
+    """
+    A participant class, describing the participants table.
+
+    Attributes
+    ----------
+    id: int
+        The primary key for this table.
+    username: str(64)
+        The primary pseudoanonymous identifier for each participants.
+        For true participants, these were assigned by E4 Connect as usernames for Empatica Studies
+        and had the form of uploader_0123456.
+    password_hash: str(128)
+    token: str(32)
+        Authentication is implemented using HTTP Basic Auth and tokens are provided for this purpose.
+    token_expiration_utc: datetime
+        Tokens expire after a preset time period.
+    collection_start_utc: datetime
+        A datetime of the first data point uploaded.
+    last_upload_utc: datetime
+        A datetime of the last data point uploaded.
+    day_count_uploaded: str
+        Days between last_upload_utc and collection_start_utc.
+    last_known_device_id: str(36)
+        Device (installation) ID that was last seen in the data.
+    active: bool
+        Is participant marked as active (i.e. collecting data)?
+    marked_active_utc: datetime
+        The time participant was first marked as active.
+    day_count_active: int
+        Days from marked_active_utc
+    tester: bool
+        Is this a tester (or a true participant)?
+    """
     __tablename__ = "participants"
     id = Column(Integer, primary_key=True)
     username = Column(String(64), index=True, unique=True)
@@ -40,6 +73,29 @@ class Participant(Base):
 
 
 class AWAREsensor(object):
+    """
+    A general AWARE sensor class. It includes fields common to all tables/subclasses.
+
+    Attributes
+    ----------
+    id: int
+        The primary key for each table.
+    _id: int
+        The original primary key, used in device's own MySQL database.
+    timestamp: int
+        Unixtime milliseconds since 1970.
+    device_id: str(36)
+        AWARE device UUID, a unique string of length 36.
+        Rather than identifying the device as the name suggests, this string changes on each (re)installation.
+        It is therefore better considered to be an installation ID.
+
+    Declared Attributes
+    -------------------
+    __tablename__: str
+        Table name used in the database.
+    participant_id: int
+        The foreign key relating (with the relationship) tables to the participants table.
+    """
     id = Column(BigInteger, primary_key=True, nullable=False)
     _id = Column(BigInteger, nullable=False)
     timestamp = Column(BigInteger, nullable=False)
@@ -137,6 +193,18 @@ class Bluetooth(Base, AWAREsensor):
 
 
 class Call(Base, AWAREsensor):
+    """
+    Contains the calls sensor information.
+
+    Attributes
+    ----------
+    call_type: int
+        One of the Android’s call types (1 – incoming, 2 – outgoing, 3 – missed).
+    call_duration: int
+        Length of the call session.
+    trace: str(40)
+        A hash value SHA-1 of the phone number (source or target) of the call
+    """
     call_type = Column(SmallInteger, nullable=False)
     call_duration = Column(Integer, nullable=False)
     trace = Column(String(length=40), nullable=True)