diff --git a/timestring.js b/timestring.js
index 23c3c2e..fc1dee1 100644
--- a/timestring.js
+++ b/timestring.js
@@ -71,14 +71,14 @@
 
         unitsRegExp = '(' +
             unitsRegExp
-                .replace(/,/g, '|')
-                .replace('|', '')
+                .replace(/,/g, '|') // convert commas to pipes
+                .replace('|', '') // removing leading pipe
             + ')';
 
         // split string into groups and get total seconds for each group
         var groups = string
                         .replace(/[^\w+-]+/g, '') // remove white space
-                        .match(/[-+]?[0-9]*\.?[0-9]+\D/g);
+                        .match(/[-+]?[0-9]*\.?[0-9]+\D/g); // match time groups (digit followed by time unit - i.e 5d 15m = 2 time groups)
 
         if (groups !== null) {
             for(var group in groups) {