Hi Anna, it means Your mileage may vary, or something to that effect. you can search google and get more info if you wish. best wishes, Michael On Jun 13, 2004, at 11:21 AM, Anna Dembska wrote: Thanks to everyone who gave their suggestions about inverters that might work with a car and a powerbook. Idecided to go with a150 watt Tripplite to make sure i have enough power. I'm actually not using it in my car, but with a battery pack in my house sans electricity. But I have one question: what does YMMV mean? Anna