diff --git a/src/router.js b/src/router.js
index 618763d..0599f08 100644
--- a/src/router.js
+++ b/src/router.js
@@ -5,8 +5,12 @@ var _ = require('underscore')
 var low = require('lowdb')
 var utils = require('./utils')
 
+// Add methods to lowdb
 low.mixin(require('underscore-db'))
 low.mixin(require('underscore.inflections'))
+
+// Override underscore-db's createId with utils.createId
+// utils.createId can generate incremental id or uuid
 low.mixin({createId: utils.createId})
 
 module.exports = function(source) {