diff --git a/full-description.md b/full-description.md
index 7aa7881..f5c662f 100644
--- a/full-description.md
+++ b/full-description.md
@@ -79,10 +79,14 @@ Categories are slightly different. You might start to notice how some things don
 
 If you spend a certain amount on the same type of things _every month_, it's a budget. Bills are a budget. Groceries are a budget. "Going out" is a budget.
 
-First and foremost: a category is incidental. 
+First and foremost: a category is incidental. You don't buy new furniture every month but you might want to keep track of such expenses. Or you don't care about costs for public traffic (budget-wise) but a category would be nice.
+
+The rule of thumb is: would you make a real life envelope for it? If yes: budget. If no: category.
 
 ## Tags
 
+Tags are an extension of categories and meant to expand on the meta-data included in a transaction. Not yet functional though.
+
 ## Piggy banks
 
 ## Recurring transactions