diff --git a/tutorial/01.markdown b/tutorial/01.markdown
index 2be950b..75e6e9e 100644
--- a/tutorial/01.markdown
+++ b/tutorial/01.markdown
@@ -4,7 +4,7 @@ The essence of a key-value store is the ability to store some data,
 called a value, inside a key. This data can later be retrieved only if we know
 the exact key used to store it.
 
-Often Redis it is called a data structure server because it has outer key-value shell, but each
+Often Redis it is called a data structure server because it has an outer key-value shell, but each
 value can contain a complex data structure, such as a string, a list, a hashes, or ordered data
 structures called sorted sets as well as probabilistic data structures like hyperloglog.