diff --git a/01-What-is-Unix.Rmd b/01-What-is-Unix.Rmd
index 84d42703..937edbb1 100644
--- a/01-What-is-Unix.Rmd
+++ b/01-What-is-Unix.Rmd
@@ -19,3 +19,4 @@ said: "With great power comes great responsibility."
 
 There are several popular shell programs but in this book we'll be using a shell 
 called Bash because it is the default shell program on Mac and Ubuntu.
+We use terminal in Ubuntu linux to write commands.