diff --git a/cli/tree.c b/cli/tree.c
new file mode 100644
index 0000000..04922e6
--- /dev/null
+++ b/cli/tree.c
@@ -0,0 +1,116 @@
+#include <assert.h>
+#include <stdlib.h>
+
+#include "curse.h"
+#include "tree.h"
+
+/* Internal allocator method for crs_node structures.
+ */
+static inline struct crs_node *__alloc_node(const enum crs_nodetype type) {
+  struct crs_node *node = (struct crs_node *)malloc(sizeof(struct crs_node));
+  node->type = type;
+  return node;
+}
+
+/* Construct a new window node (crs_node of type NODE_WIN).
+ */
+static struct crs_node *init_node_window(WINDOW *win) {
+  struct crs_node *node = __alloc_node(NODE_WINDOW);
+  node->win = win;
+
+  return node;
+}
+
+static struct crs_node *init_node_abstract(struct crs_node *node1,
+                                           struct crs_node *node2,
+                                           float ratio) {
+  struct crs_node *node = __alloc_node(NODE_ABSTRACT);
+  node->ratio = ratio;
+
+  node->child[0] = node1;
+  node->child[1] = node2;
+  return node;
+}
+
+static void destroy_node(struct crs_node *node) {
+  if (node->type == NODE_WINDOW) {
+    /* Window Node */
+    delwin(node->win);
+    goto end;
+  }
+  /* Abstract Node */
+  destroy_node(node->child[0]);
+  destroy_node(node->child[1]);
+
+end:
+  free(node);
+}
+
+/* Subdivide a window node's allocated region into two window nodes
+ * replacing the original node with an abstract node.
+ * Parameters:
+ *   axis   - controls which direction the subdivision occurs
+ *   invert - invert index of the original node in the new abstract node
+ */
+static void bifurcate_window_node(struct crs_node **node, enum crs_axis axis,
+                                  int invert, float ratio) {
+  assert((*node)->type == NODE_ABSTRACT);
+
+  struct crs_node *original_node = *node;
+  struct crs_node *bi_node = init_node_window(); // WARNING: TODO
+
+  if (!invert) {
+    /* Inverted Bifurcation */
+    *node = init_node_abstract(bi_node, original_node, ratio);
+  } else {
+    /* Non-Inverted Bifurcation */
+    *node = init_node_abstract(original_node, bi_node, ratio);
+  }
+
+  resize_abstract_node(*node);
+}
+
+/* Collapse an abstract node, killing one child node and resizing
+ * the other to take its place.
+ */
+static void collapse_abstract_node(struct crs_node **node,
+                                   const int collapse_i) {
+  assert((*node)->type == NODE_ABSTRACT);
+  assert(0 <= collapse_i && collapse_i < NODE_CHILD_N);
+
+  // WARNING: only works for NODE_CHILD_N=2 (binary trees)
+  destroy_node((*node)->child[!collapse_i]);
+
+  struct crs_node *collapse_target = (*node)->child[collapse_i];
+  free(*node);
+  *node = collapse_target;
+}
+
+/*
+ */
+static struct crs_node *init_root_node(void) {
+  WINDOW *rootwin = newwin(0, 0, 0, 0);
+  return init_node_window(rootwin);
+}
+
+int init_tree(struct crs_tree **tree) {
+  *tree = (struct crs_tree *)malloc(sizeof(struct crs_tree));
+
+  /* Initialise NCurses Library & Standard Screen */
+  crs_init(&(*tree)->stdscr);
+
+  /* */
+  (*tree)->root = init_root_node();
+
+  // (*tree)->root = __alloc_node(NODE_WINDOW);
+  // crs_init(&(*tree)->root->win);
+
+  return EXIT_SUCCESS;
+}
+
+void destroy_tree(struct crs_tree *tree) {
+  /* WARNING: is it ok to delwin(stdscr) ?? */
+  destroy_node(tree->root);
+
+  endwin();
+}
diff --git a/cli/tree.h b/cli/tree.h
new file mode 100644
index 0000000..d5ba171
--- /dev/null
+++ b/cli/tree.h
@@ -0,0 +1,58 @@
+#ifndef DORNE_TREE_H
+#define DORNE_TREE_H
+
+# ifndef __NCURSES_H
+typedef struct _win_st WINDOW;
+# endif /* __NCURSES_H */
+
+#define NODE_CHILD_N 2
+
+/* MACRO:
+ * void NODEDIMS(struct crs_node *node, struct crs_nodedims dims);
+ */
+#define NODEDIMS(node, dims) (getbegyx(dims.y, dims.x); getmaxyx(dims.y, dims.x))
+
+enum crs_nodetype {
+  NODE_WINDOW,
+  NODE_ABSTRACT,
+};
+
+/* Stores a node's starting x,y coordinates, width, & height.
+ * NOTE: Intended for interfunction communication.
+ */
+struct crs_nodedims {
+  int x, y, width, height;
+};
+
+enum crs_axis {
+  AXIS_X,
+  AXIS_Y,
+};
+
+struct crs_node {
+  enum crs_nodetype type;
+  // union value depends on crs_node.type
+  union {
+    WINDOW *win;
+    struct {
+      float ratio;
+      struct crs_node *child[NODE_CHILD_N];
+    };
+  };
+};
+
+struct crs_tree {
+  WINDOW *stdscr;
+  struct crs_node *root;
+};
+
+/* === External Interface === */
+// struct crs_node *init_node_window(void);
+// struct crs_node *init_node_abstract(void);
+// void destroy_node(struct crs_node *node);
+
+int init_tree(struct crs_tree **tree);
+void update_tree(struct crs_tree *tree);
+void destroy_tree(struct crs_tree *tree);
+
+#endif /* DORNE_TREE_H */