"Some believe that decanting wine is a practice that should only occur when an aged wine needs to be separated from the fine sediment (carefully!). French oenologist Émile Peynaud went as far as to say it was harmful to wines to decant them but many sommeliers would disagree.
We know that decent wine has the ability to age and improve, sometimes for years. So much of the wine we buy is to be drunk now, but most of it will be better with a few more years in bottle. If you don't want to wait to drink younger wines, try decanting first as exposure to the air seems to help to wake up a wine in my experience. Its particular characters become more expressive over the few hours you're drinking it. The tanins soften and the aromas appear more pronounced.
I suggest you try this yourself, simply pouring a glass or two one evening and paying attention to how it tastes, then pop in the cork, put the bottle in the fridge and try a few glasses the next evening. The exposure to oxygen allowed into the bottle overnight will simulate the effect of decanting. You may well find that the wine has become more fragrant and rounder. It has woken up.
I decant both red and white - pouring it out into a decanter or sometimes, rather unceremoniously, into a pyrex jug and give it a while before I dig in. We recently stocked a bin-end that was 6 years old and after decanting we found that it had mellowed and become more complex with age and these characteristics were evident as it was enthusiastically appreciated by one and all."