diff --git a/src/mind_reader/domain/__init__.py b/src/mind_reader/domain/__init__.py
new file mode 100644
index 0000000..94c3840
--- /dev/null
+++ b/src/mind_reader/domain/__init__.py
@@ -0,0 +1,20 @@
+from .common import Player, PlayerRole
+from .session import (
+    ArrowDirection,
+    CardData,
+    CardState,
+    SessionStats,
+    StepData,
+    StepState,
+)
+
+__all__ = [
+    "Player",
+    "PlayerRole",
+    "ArrowDirection",
+    "CardData",
+    "CardState",
+    "SessionStats",
+    "StepData",
+    "StepState",
+]
diff --git a/src/mind_reader/domain/common.py b/src/mind_reader/domain/common.py
new file mode 100644
index 0000000..6a976f9
--- /dev/null
+++ b/src/mind_reader/domain/common.py
@@ -0,0 +1,13 @@
+from dataclasses import dataclass
+from enum import Enum, auto
+
+
+class PlayerRole(Enum):
+    SETTER = auto()
+    GUESSER = auto()
+
+
+@dataclass
+class Player:
+    name: str
+    role: PlayerRole
diff --git a/src/mind_reader/domain.py b/src/mind_reader/domain/session.py
similarity index 88%
rename from src/mind_reader/domain.py
rename to src/mind_reader/domain/session.py
index 4be2c48..41fb5bd 100644
--- a/src/mind_reader/domain.py
+++ b/src/mind_reader/domain/session.py
@@ -3,6 +3,17 @@ from enum import Enum, auto
 from typing import Optional
 
 
+class ArrowDirection(Enum):
+    LEFT = auto()
+    RIGHT = auto()
+
+
+class StepState(Enum):
+    WAITING_FOR_SETTER = auto()
+    WAITING_FOR_GUESSER = auto()
+    SESSION_FINISHED = auto()
+
+
 class CardState(Enum):
     SETTER_NOT_SET = auto()
     SETTER_HIDDEN = auto()
@@ -13,9 +24,17 @@ class CardState(Enum):
     GUESSER_WRONG = auto()
 
 
-class ArrowDirection(Enum):
-    LEFT = auto()
-    RIGHT = auto()
+@dataclass(frozen=True)
+class CardData:
+    direction: Optional[ArrowDirection]
+    state: CardState
+
+
+@dataclass(frozen=True)
+class StepData:
+    index: int
+    setter: CardData
+    guesser: CardData
 
 
 @dataclass
@@ -33,33 +52,3 @@ class SessionStats:
             accuracy = 0.0
         accuracy = (self.correct / self.total) * 100
         return round(accuracy, 1)
-
-
-class StepState(Enum):
-    WAITING_FOR_SETTER = auto()
-    WAITING_FOR_GUESSER = auto()
-    SESSION_FINISHED = auto()
-
-
-class PlayerRole(Enum):
-    SETTER = auto()
-    GUESSER = auto()
-
-
-@dataclass(frozen=True)
-class CardData:
-    direction: Optional[ArrowDirection]
-    state: CardState
-
-
-@dataclass(frozen=True)
-class StepData:
-    index: int
-    setter: CardData
-    guesser: CardData
-
-
-@dataclass
-class Player:
-    name: str
-    role: PlayerRole