diff --git a/School/Development/SQL Database.md b/School/Development/SQL Database.md
index 5389516..bc5337f 100644
--- a/School/Development/SQL Database.md	
+++ b/School/Development/SQL Database.md	
@@ -21,7 +21,13 @@ An entity represents a real-world object or concept. Examples are: Employee, Pro
 
 ## Entity
 
-An entity is the 
+An entity contains attributes that have values. For example, an entity Person may have the following attributes: Name, Age, Sex, etc..
+
+## Entity Set
+
+A entity set is a collection of entities that share the same attributes. The entities within the set are distinguishable from each other because the values that the attributes have differ.
+
+