What is the essential feature of a flourish in calligraphy?

The essential feature of a flourish in calligraphy is that it serves as an additional decorative element. Flourishes enhance the visual appeal of the lettering by adding artistic embellishments that are more ornate than standard strokes. They can take the form of swirls, loops, and other intricate designs that complement the main letterforms, creating a sense of elegance and artistry within the calligraphy.

This decorative aspect is crucial as it elevates the overall presentation of the text, making it more engaging and visually striking. Flourishes can help to guide the viewer's eye and contribute to the rhythm of the written piece, thus playing an integral role in the aesthetic qualities of calligraphy.