diff --git a/src/structs/tuple-structs.md b/src/structs/tuple-structs.md
index 0e8ea6af..4ac7e07c 100644
--- a/src/structs/tuple-structs.md
+++ b/src/structs/tuple-structs.md
@@ -31,3 +31,11 @@ fn main() {
 }
 
 ```
+
+<details>
+
+Newtypes are a great way to encode additional information about the value in a primitive type, for example:
+  * The number is measured in some units: `Newtons` in the example above.
+  * The value passed some validation when it was created, so you no longer have to validate it again at every use: 'PhoneNumber(String)` or `OddNumber(u32)`.
+    
+</details>