diff --git a/README.md b/README.md
index 34ef455..58452e5 100644
--- a/README.md
+++ b/README.md
@@ -6,3 +6,23 @@
 ```
 $ ./fetch_externals.py
 ```
+
+The script will build following tree structure.
+
+```
+Directory               Repository
+.                       https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u
++-- core_software       https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-core-driver
+|   +-- core_driver     https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-core-software
+|   +-- cmsis           GitHub
+|   +-- tensorflow      GitHub
++-- vela                https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-vela
+```
+
+| Directory | Description |
+--- | ---
+| .             | This is the root directory for all Ethos-u software. |
+| core_software | The software executing on Arm Cortex-M is referred to as _Core Software_. This folder provides a small build system that illustrates how to build the key components for the Ethos-u core software. |
+| cmsis         | CMSIS provides optimized kernels and generic interfaces to the Arm Cortex-M CPUs. |
+| tensorflow    | The TensorFlowLite micro framework is used to run inferences. |
+| vela          | The Vela optimizer takes a TFLu file as input and replaces operators that are supported by the Ethos-u NPU with custom operators designed to run on the NPU. Operators not supported by the NPU are executed in software. |