diff --git a/include/vieter_tree.h b/include/vieter_tree.h
new file mode 100644
index 0000000..7dda9e1
--- /dev/null
+++ b/include/vieter_tree.h
@@ -0,0 +1,15 @@
+#ifndef VIETER_TREE
+#define VIETER_TREE
+
+#include <stdint.h>
+
+typedef struct vieter_tree vieter_tree;
+
+typedef enum vieter_tree_error {
+    vieter_tree_ok = 0,
+    vieter_tree_already_present = 1
+} vieter_tree_error;
+
+vieter_tree_error vieter_tree_insert(uint64_t key, void *data);
+
+#endif
diff --git a/src/tree/node.h b/src/tree/node.h
new file mode 100644
index 0000000..10143ca
--- /dev/null
+++ b/src/tree/node.h
@@ -0,0 +1,13 @@
+#ifndef VIETER_BALANCED_TREE_NODE
+#define VIETER_BALANCED_TREE_NODE
+
+#include <stdint.h>
+
+typedef struct vieter_tree_node {
+    uint64_t key;
+    void *data;
+    struct vieter_tree_node *left;
+    struct vieter_tree_node *right;
+} vieter_tree_node;
+
+#endif
diff --git a/src/tree/tree.c b/src/tree/tree.c
new file mode 100644
index 0000000..4a10d5a
--- /dev/null
+++ b/src/tree/tree.c
@@ -0,0 +1,6 @@
+#include "vieter_tree.h"
+#include "node.h"
+
+struct vieter_tree {
+    uint64_t size;
+};