diff --git a/src/doc/book/primitive-types.md b/src/doc/book/primitive-types.md
index d6188fa7cdcf..9378632987a2 100644
--- a/src/doc/book/primitive-types.md
+++ b/src/doc/book/primitive-types.md
@@ -164,6 +164,9 @@ copying. For example, you might want to reference just one line of a file read
 into memory. By nature, a slice is not created directly, but from an existing
 variable binding. Slices have a defined length, can be mutable or immutable.
 
+Internally, slices are represented as a pointer to the beginning of the data 
+and a length.
+
 ## Slicing syntax
 
 You can use a combo of `&` and `[]` to create a slice from various things. The