The colour can tell you a lot about the wine. It can tell you how old or young a wine is. White wines tend to gain colour as they age, and red wines lose colour as they age. For example, if you uncork an aged white wine, the colour of the wine will be more towards yellow rather than a pale straw colour. Similarly, with red wines, you will see them becoming lighter, and sometimes, if the wine has been through a bit of oxidation, it can become brown.