A good guitar improves with age, guitar strings however do not. Aging guitar strings have their playability, tone and intonation negatively affected by buildup of dirt, sweat and oils found naturally in our fingers. The strings will start to sound dull, play more difficult and break more easily. Changing your strings for a fresh set will make sure it plays easy, sounds better and brighter and stay in tune for allot longer. Signs that your strings need changing are easily recognised by discoloration and a lackluster sound, also if you have an important gig comming up, it's best to put on a fresh set of strings.