diff --git a/docs/01-rainbow-triangle.md b/docs/01-rainbow-triangle.md
index 2b5fbcf..e837ce1 100644
--- a/docs/01-rainbow-triangle.md
+++ b/docs/01-rainbow-triangle.md
@@ -432,6 +432,16 @@ becomes a [command buffer](concepts/GLOSSARY.md#command-buffer) that is submitte
 to this queue. On Vulkan, the device corresponds to `VkDevice` and the queue
 to a `VkQueue`.
 
+> **Key insight — Validation layers catch GPU errors at runtime:** wgpu ships
+> with built-in validation layers that inspect your API calls for common
+> mistakes: incorrect buffer bindings, mismatched pipeline state, out-of-bounds
+> buffer slices, and resource lifecycle violations. These layers run
+> automatically during development and surface errors as log messages or
+> panics, saving hours of debugging silent GPU corruption. The tradeoff:
+> validation adds measurable overhead to every frame. In release builds,
+> disable validation by setting `DeviceDescriptor::device_type` or using
+> the `WGPU_BACKEND` environment variable to skip the validation path.
+
 **Step 5 — SurfaceConfiguration:** This allocates the
 [swapchain](concepts/GLOSSARY.md#swapchain) [framebuffers](concepts/GLOSSARY.md#framebuffer).
 We negotiate the pixel format with the driver (preferring an