The Lydian mode is a musical scale characterized by its unique sequence of whole and half steps, specifically defined as W-W-W-H-W-W-H, where 'W' represents a whole step and 'H' represents a half step. This mode is notable for its raised fourth scale degree, which contributes to its distinctive sound that evokes a sense of brightness and uplifting emotion. In the context of Renaissance music, the Lydian mode played an essential role in shaping melodies and harmonies that were commonly used during this period.