It's no secret that decanting will allow your wine to aerate which allows the aromas and flavors to become more vibrant again! Another reason for decanting is some wines have sediment in the bottle and by pouring wine carefully into a decanter you can separate the sediment. DON'T BE FOOLED by wines that have sediment--it does not mean the wine has gone bad! You have to open the bottle and check! Most sediment is simply byproducts from the process of making wines and is also common in older vintages.
What age do you decant you ask? I say all reds could benefit from a little decanting--plus, remember, we are common people attempting to make wine drinking and serving not so intimidating! Go antiquing and find an old glass decanter to add style to your table---it's functional and you'll look cool too!