diff --git a/Chapter04/Cargo.toml b/Chapter04/Cargo.toml
new file mode 100644
index 0000000..d935a84
--- /dev/null
+++ b/Chapter04/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "Chapter4"
+version = "1.0.0"
+
+[dependencies]
+
+[[bin]]
+name = "generics"
+path = "generics.rs"
+
+[[bin]]
+name = "polymorphism"
+path = "polymorphism.rs"
diff --git a/Chapter04/generics.rs b/Chapter04/generics.rs
new file mode 100644
index 0000000..46f05b8
--- /dev/null
+++ b/Chapter04/generics.rs
@@ -0,0 +1,86 @@
+struct Cat
+{
+   weight: f64,
+   speed: f64
+}
+
+struct Dog
+{
+   weight: f64,
+   speed: f64
+}
+
+trait Animal
+{
+   fn max_speed(&self) -> f64;
+}
+
+impl Animal for Cat
+{
+   fn max_speed(&self) -> f64
+   {
+      self.speed
+   }
+}
+
+impl Animal for Dog
+{
+   fn max_speed(&self) -> f64
+   {
+      self.speed
+   }
+}
+
+struct SqueakyToy
+{
+   weight: f64
+}
+
+struct Stick
+{
+   weight: f64
+}
+
+trait Toy
+{
+   fn weight(&self) -> f64;
+}
+
+impl Toy for SqueakyToy
+{
+   fn weight(&self) -> f64
+   {
+      self.weight
+   }
+}
+
+impl Toy for Stick
+{
+   fn weight(&self) -> f64
+   {
+      self.weight
+   }
+}
+
+struct AnimalChasingToy<A: Animal, T: Toy>
+{
+   animal: A,
+   toy: T
+}
+
+trait AnimalChasesToy<A: Animal, T: Toy>
+{
+   fn chase(&self);
+}
+
+impl<A: Animal, T: Toy> AnimalChasesToy<A, T> for AnimalChasingToy<A, T>
+{
+   fn chase(&self)
+   {
+      println!("chase")
+   }
+}
+
+fn main()
+{
+}
diff --git a/Chapter04/polymorphism.rs b/Chapter04/polymorphism.rs
new file mode 100644
index 0000000..fe0c7d1
--- /dev/null
+++ b/Chapter04/polymorphism.rs
@@ -0,0 +1,43 @@
+use std::ops::Mul;
+
+fn raise_by_three<T: Mul + Copy>(x: T) -> T
+where T: std::ops::Mul<Output=T>
+{
+   x * x * x
+}
+
+#[derive(Copy, Clone)]
+struct Raiseable<T: Mul + Copy>
+{
+  x: T
+}
+impl<T: Mul + Copy> std::ops::Mul for Raiseable<T>
+where T: std::ops::Mul<Output=T>
+{
+   type Output = Raiseable<T>;
+   fn mul(self, rhs: Self) -> Self::Output
+   {
+      Raiseable { x: self.x * rhs.x }
+   }
+}
+
+fn main()
+{
+
+   raise_by_three(10);
+   (10 as u64).pow(3);
+
+   raise_by_three(3.0);
+   (3.0 as f64).powi(3);
+
+   let x = Raiseable { x: 10 as u64 };
+   raise_by_three(x);
+   //no method named pow
+   //x.pow(3);
+
+   let x = Raiseable { x: 3.0 as f64 };
+   raise_by_three(x);
+   //no method named powi
+   //x.powi(3);
+
+}