diff --git a/18-rendering-with-rays/README.md b/18-rendering-with-rays/README.md
new file mode 100644
index 0000000..8f5ff56
--- /dev/null
+++ b/18-rendering-with-rays/README.md
@@ -0,0 +1,80 @@
+# Chapter 18: Rendering with Rays
+
+As I read this book, I summarize what I think is wrong. If you think my comments are wrong then please let me know. We can dicuss more and update your opinion.
+
+## Signed distance functions
+
+There is a runtime error in because Shaders.metal files isn't included in the bundle. But we have the default library.
+
+In Renderer.swift, in initializeMetal(), replace this:
+
+```
+guard let path = Bundle.main.path(forResource: "Shaders", ofType: "metal") else { fatalError() }
+let input = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
+let library = try device.makeLibrary(source: input, options: nil)
+```
+
+With:
+
+```
+let library = device.makeDefaultLibrary()!
+```
+
+## The raymarching algorithm
+
+There is a runtime error in because Shaders.metal files isn't included in the bundle. But we have the default library.
+
+In Renderer.swift, in initializeMetal(), replace this:
+
+```
+guard let path = Bundle.main.path(forResource: "Shaders", ofType: "metal") else { fatalError() }
+let input = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
+let library = try device.makeLibrary(source: input, options: nil)
+```
+
+With:
+
+```
+let library = device.makeDefaultLibrary()!
+```
+
+## Creating random noise
+
+There is a runtime error in because Shaders.metal files isn't included in the bundle. But we have the default library.
+
+In Renderer.swift, in initializeMetal(), remove this:
+
+```
+let path = Bundle.main.path(forResource: "Shaders", ofType: "metal")
+```
+
+Replace this:
+
+```
+let input = try String(contentsOfFile: path!, encoding: String.Encoding.utf8)
+let library = try device!.makeLibrary(source: input, options: nil)
+```
+
+With:
+
+```
+let library = device.makeDefaultLibrary()!
+```
+
+## Marching clouds
+
+There is a runtime error in because Shaders.metal files isn't included in the bundle. But we have the default library.
+
+In Renderer.swift, in initializeMetal(), replace this:
+
+```
+guard let path = Bundle.main.path(forResource: "Shaders", ofType: "metal") else { fatalError() }
+let input = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
+let library = try device.makeLibrary(source: input, options: nil)
+```
+
+With:
+
+```
+let library = device.makeDefaultLibrary()!
+```
diff --git a/README.md b/README.md
index 309012b..39abb7c 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ You can see color images in this book at [here](https://www.raywenderlich.com/bo
  * [Chapter 14: Multipass & Deferred Rendering](https://github.com/daemyung/metal-by-tutorials/tree/main/14-multipass-rendering)
  * [Chapter 15: GPU-Driven Rendering](https://github.com/daemyung/metal-by-tutorials/tree/main/15-gpu-driven-rendering)
  * [Chapter 16: Particle Systems](https://github.com/daemyung/metal-by-tutorials/tree/main/16-particle-systems)
+ * [Chapter 18: Rendering with Rays](https://github.com/daemyung/metal-by-tutorials/tree/main/18-rendering-with-rays)
 
 ## Copyright