What is the purpose of having a wound 3rd string?
A wound 3rd string is typically heavier in gauge compared to a plain 3rd string. For an electric guitar, the purpose of having a wound 3rd string is to soften the brightness of tone, in contrast to an unwound (or plain) 3rd string. Many acoustic string sets come with a wound 3rd string to help improve vibrational energy transfer to the sound board through the bridge.
