Merchants have learned to abuse (use) that difference between an auth and a capture.  Sometimes you will get auths that differ from the actual capture.  Some examples (all US centered):<p>1) Restaurants will auth your credit card for the bill total, but will capture for bill + tip.  So pre-settled totals will not include tip.<p>2) Gas stations auth your card when you scan (before the pump turns on).  They auth for $100, but will then capture for whatever amount you spend.<p>3) When you add a card to certain merchants (like the Google Play store), they will do a 1 cent auth to make sure the card&#x2F;address&#x2F;expiration are valid.  But then they never issue the capture and the event disappears.