Decanting is often regarded as a snob process for making wine look fancy. It’s not! It is a very effective way of separating wine from accumulated sediments and allowing a little air to mix with and improve a wine that has been bottled up for a long time to regain some of its freshness.
You can make it expensive if you so desire with cut glass decanters, special slow pouring contraptions and candles. Alternatively a clean bottle, funnel and inverted torch will do just fine!
Firstly, decanting makes wine serving a whole lot easier. By separating the sediment from the wine allows a much easier wine pouring process at the table and prevents spoiling much of the wine with stirred up sediment.
Secondly the aeration and exposure to air (which can occur over a couple of hours) often helps to bring out more of the flavours that have been locked away for many years and potentially soften the wine texture and tannins. Furthermore, if you choose to use a nice glass decanter, it can present the wine very elegantly.
A simple so called “double decanting” process can be used to slowly and carefully pour out the contents (not sediment) through a funnel into a clean bottle and then after water only rinsing, back into the original bottle for serving.