diff --git a/pathfinding3d/core/diagonal_movement.py b/pathfinding3d/core/diagonal_movement.py
index 831f957..a4b8d7f 100644
--- a/pathfinding3d/core/diagonal_movement.py
+++ b/pathfinding3d/core/diagonal_movement.py
@@ -1,4 +1,5 @@
 class DiagonalMovement:
+    """Enum for diagonal movement"""
     always = 1
     never = 2
     if_at_most_one_obstacle = 3
diff --git a/pathfinding3d/core/grid.py b/pathfinding3d/core/grid.py
index 5811486..a841824 100644
--- a/pathfinding3d/core/grid.py
+++ b/pathfinding3d/core/grid.py
@@ -42,7 +42,7 @@ def build_nodes(
 
     Returns
     -------
-    List
+    List[List[List[GridNode]]]
         A list of list of lists containing the nodes in the grid.
     """
     nodes: List = []
@@ -67,6 +67,9 @@ def build_nodes(
 
 
 class Grid:
+    """
+    A grid represents the map (as 3d-list of nodes).
+    """
     def __init__(
         self,
         width: int = 0,
@@ -77,7 +80,7 @@ def __init__(
         inverse: bool = False,
     ):
         """
-        A grid represents the map (as 3d-list of nodes).
+        Create a new grid.
 
         Parameters
         ----------
@@ -115,6 +118,14 @@ def _validate_dimensions(self, width: int, height: int, depth: int, matrix: Matr
         return width, height, depth
 
     def is_valid_grid(self) -> bool:
+        """
+        Check if grid is valid
+
+        Returns
+        -------
+        bool
+            True, if grid is valid
+        """
         return self.width > 0 and self.height > 0 and self.depth > 0
 
     def node(self, x: int, y: int, z: int) -> Optional[GridNode]:
@@ -247,8 +258,8 @@ def neighbors(
 
         Returns
         -------
-        list
-            list of neighbor nodes
+        List[GridNode]
+            list of all neighbors
         """
         x, y, z = node.x, node.y, node.z
 
diff --git a/pathfinding3d/core/node.py b/pathfinding3d/core/node.py
index bf66f24..c663b8c 100644
--- a/pathfinding3d/core/node.py
+++ b/pathfinding3d/core/node.py
@@ -4,6 +4,28 @@
 
 @dataclasses.dataclass
 class Node:
+    """
+    Basic node class, saves calculated values for pathfinding
+
+    Attributes
+    ----------
+    h : float
+        The cost from this node to the goal (for A* including the heuristic).
+    g : float
+        The cost from the start node to this node.
+    f : float
+        The overall cost for a path using this node (f = g + h).
+    opened : int
+        The number of times this node has been opened.
+    closed : bool
+        Whether this node is closed.
+    parent : Optional[Node]
+        The parent node of this node.
+    retain_count : int
+        Used for recursion tracking of IDA*.
+    tested : bool
+        Used for IDA* and Jump-Point-Search.
+    """
     __slots__ = ["h", "g", "f", "opened", "closed", "parent", "retain_count", "tested"]
 
     def __init__(self):
@@ -41,8 +63,24 @@ def cleanup(self):
 @dataclasses.dataclass
 class GridNode(Node):
     """
-    basic node, saves X, Y and Z coordinates on some grid and determine if
-    it is walkable.
+    Basic node in a grid.
+
+    Attributes
+    ----------
+    x : int
+        The x coordinate of the node.
+    y : int
+        The y coordinate of the node.
+    z : int
+        The z coordinate of the node.
+    walkable : bool
+        Whether this node can be walked through.
+    weight : float
+        The weight of the node.
+    grid_id : Optional[int]
+        The id of the grid this node belongs to.
+    connections : Optional[List]
+        The connections of this node.
     """
 
     # Coordinates
@@ -64,8 +102,6 @@ class GridNode(Node):
 
     connections: Optional[List] = None
 
-    identifier: Optional[Tuple] = None
-
     def __post_init__(self):
         super().__init__()
         # for heap
@@ -81,6 +117,14 @@ def __iter__(self):
             yield self.grid_id
 
     def connect(self, other_node: "GridNode"):
+        """
+        Connect this node to another node.
+
+        Parameters
+        ----------
+        other_node : GridNode
+            The node to connect to.
+        """
         if not self.connections:
             self.connections = [other_node]
         else:
diff --git a/pathfinding3d/core/world.py b/pathfinding3d/core/world.py
index 0f033fb..aac91aa 100644
--- a/pathfinding3d/core/world.py
+++ b/pathfinding3d/core/world.py
@@ -6,7 +6,18 @@
 
 # a world connects grids but can have multiple grids.
 class World:
+    """
+    A world connects grids but can have multiple grids.
+    """
     def __init__(self, grids: Dict[int, Grid]):
+        """
+        Initialize a new world.
+
+        Parameters
+        ----------
+        grids : Dict[int, Grid]
+            grids in this world
+        """
         self.grids = grids
 
     def neighbors(self, node: GridNode, diagonal_movement: int) -> List[GridNode]: