Most people have seen wine poured from glass vessels, but probably never knew what it was called. Decanting is pouring wine from one bottle into a separate container. We generally do this because a decanter, or a glass container designed for decanting, does a better job at exposing the wine to oxygen.
If you drink a lot of wine at home, you will probably want to buy a decanter. They typically have a narrow neck and a wide base. You can some reasonably priced decanters.
If you want to learn more about wine aeration, check out the following article: