#84 Added pattern description

layers/index.md

@@ -0,0 +1,19 @@
+---
+layout: pattern
+title: Layers
+folder: layers
+permalink: /patterns/layers/
+categories: pattern_cat
+tags: pattern_tag
+---
+
+**Intent:** Layers is an architectural style where software responsibilities are
+ divided among the different layers of the application.
+
+![alt text](./etc/layers.png "Layers")
+
+**Applicability:** Use the Layers architecture when
+
+* you want clearly divide software responsibilities into differents parts of the program
+* you want to prevent a change from propagating throughout the application
+* you want to make your application more maintainable and testable