Airlines have three kinds of outlets: standard North American, auto cigarette lighter, and a smaller one called "emPower."

If your airline uses the first kind, you don't need anything special. That is rare in North America, but you didn't say where you're going.

Electronics/computer stores usually carry adapters for the other two. One unit usually works with both. Its cord ends in an emPower plug. A cigarette lighter adapter fits over that. It can be used in cars as well. Make sure you get the right tip to fit your laptop at the other end.

Do a search in the Travel Technology forum for many threads on the pros and cons of various brands, the pros and cons of inverters, etc., etc.