What aspect is essential to the characteristics of the waltz?

The essential characteristic of the waltz is its slow, flowing melodies that are set to a 3/4 time signature. This specific time signature, where there are three beats in each measure, creates a strong, rhythmic foundation that is fundamental to the dance's distinctive style. The flowing melodies often accompany a smooth and elegant dance movement, making the waltz easily recognizable. The three-beat pattern allows for a graceful sway that is integral to the dance, emphasizing the importance of both the rhythm and melody in the composition and performance of waltzes. This combination of a gentle, flowing melody in a three-beat structure distinguishes the waltz from other dance forms, particularly those with faster tempos or different time signatures.