diff --git a/nc_http/core/__init__.py b/nc_http/core/__init__.py
index e69de29..e7bc240 100644
--- a/nc_http/core/__init__.py
+++ b/nc_http/core/__init__.py
@@ -0,0 +1,3 @@
+"""
+core: 依赖于第三方类库的工具函数、类
+"""
diff --git a/nc_http/tools/__init__.py b/nc_http/tools/__init__.py
new file mode 100644
index 0000000..00afa53
--- /dev/null
+++ b/nc_http/tools/__init__.py
@@ -0,0 +1,3 @@
+"""
+tools: 仅依赖内建库的函数、类库
+"""
diff --git a/nc_http/trash/__init__.py b/nc_http/trash/__init__.py
new file mode 100644
index 0000000..99d67a7
--- /dev/null
+++ b/nc_http/trash/__init__.py
@@ -0,0 +1,3 @@
+"""
+trash: 尚未分类的工具函数、类
+"""
diff --git a/nc_http/utils/__init__.py b/nc_http/utils/__init__.py
index e69de29..7497b68 100644
--- a/nc_http/utils/__init__.py
+++ b/nc_http/utils/__init__.py
@@ -0,0 +1,3 @@
+"""
+utils: 依赖于 core 的类库
+"""