diff --git a/code_submitter/tables.py b/code_submitter/tables.py
index dfb7b6d..b489ecb 100644
--- a/code_submitter/tables.py
+++ b/code_submitter/tables.py
@@ -1,7 +1,11 @@
+import enum
+
 import sqlalchemy
 
 metadata = sqlalchemy.MetaData()
 
+# As a team member you upload your archives prior to their being used to
+# simulate matches.
 Archive = sqlalchemy.Table(
     'archive',
     metadata,
@@ -19,6 +23,8 @@
     ),
 )
 
+# As a team member you choose which of your uploaded archives is the one which
+# should be used for simulating matches.
 ChoiceHistory = sqlalchemy.Table(
     'choice_history',
     metadata,
@@ -34,3 +40,91 @@
         server_default=sqlalchemy.func.now(),
     ),
 )
+
+
+# At the point of downloading the archives in order to run matches, you create a
+# Session. The act of doing that will also create the required ChoiceForSession
+# rows to record which items will be contained in the download.
+Session = sqlalchemy.Table(
+    'session',
+    metadata,
+    sqlalchemy.Column('id', sqlalchemy.Integer, primary_key=True),
+    sqlalchemy.Column('description', sqlalchemy.String, nullable=False),
+
+    sqlalchemy.Column('username', sqlalchemy.String, nullable=False),
+
+    sqlalchemy.Column(
+        'created',
+        sqlalchemy.DateTime(timezone=True),
+        nullable=False,
+        server_default=sqlalchemy.func.now(),
+    ),
+)
+
+ChoiceForSession = sqlalchemy.Table(
+    'choice_for_session',
+    metadata,
+    sqlalchemy.Column(
+        'choice_id',
+        sqlalchemy.ForeignKey('choice_history.id'),
+        primary_key=True,
+    ),
+    sqlalchemy.Column(
+        'session_id',
+        sqlalchemy.ForeignKey('session.id'),
+        primary_key=True,
+    ),
+)
+
+
+# After matches have been simulated, there are a number of artefacts which
+# should be shared with the teams.
+
+class ArtefactType(enum.Enum):
+    Logs = 'logs'
+    Animations = 'animations'
+
+
+Artefact = sqlalchemy.Table(
+    'artefact',
+    metadata,
+    sqlalchemy.Column('id', sqlalchemy.Integer, primary_key=True),
+    sqlalchemy.Column('content', sqlalchemy.LargeBinary, nullable=False),
+    sqlalchemy.Column('type', sqlalchemy.Enum(ArtefactType), nullable=False),
+
+    # Compound foreign key to the ChoiceForSession. This provides a link to the
+    # team this artefact is availalbe to. When `choice_id` is null, this
+    # indicates that the artefact is available to all teams.
+    sqlalchemy.Column(
+        'choice_id',
+        sqlalchemy.ForeignKey('choice.id'),
+        nullable=True,
+    ),
+    sqlalchemy.Column(
+        'session_id',
+        sqlalchemy.ForeignKey('session.id'),
+        nullable=False,
+    ),
+    sqlalchemy.ForeignKeyConstraint(
+        ('choice_id', 'session_id'),
+        ('choice_for_session.choice_id', 'choice_for_session.session_id'),
+        # This foreign key constraint only applies when both fields are populated
+        match='SIMPLE',
+    ),
+
+    sqlalchemy.Column(
+        'created',
+        sqlalchemy.DateTime(timezone=True),
+        nullable=False,
+        server_default=sqlalchemy.func.now(),
+    ),
+)
+
+# Constrain session_id such that we only allow one globally-visible artefact
+# per session. This is to prevent accidentally uploading everything as
+# visible to everyone.
+sqlalchemy.Index(
+    'unique_globally_visible_artefact_per_session',
+    unique=True,
+    sqlite_where=Artefact.c.choice_id.is_(None),
+)