Decanting wine is when it is poured into a glass container before serving. Decanting benefits red wines especially older reds. Older red wines usually contain sediment and decanters allow the sediment to settle and make it easier to pour the wine without the sediment. Wine decanting allow the wine to breathe and may improve the flavor as the wine opens up. Younger wines also benefit from the aeration and rest that decanting provides.
Before decanting a wine that contains sediment let the bottle rest upright allowing any sediment to sink to the bottom. Then slowing pour the wine into the decanter keeping the bottle angled to prevent any sediment from making its way into the wine decanter.
Wine also benefits from additional aeration by using a wine funnel. Most funnels are made to be used with decanters and many come with a small screen to help filter out any sediment.