What characteristic distinguishes Celtic lettering from other styles?

Celtic lettering is prominently distinguished by the inclusion of intricate knotwork. This characteristic reflects the unique artistic style of Celtic culture, which often involves complex interwoven patterns that symbolize interconnectedness and eternity. These knot designs are not merely decorative; they carry cultural significance and have been integrated into various forms of art, including illuminated manuscripts and stone carvings.

This intricate knotwork sets Celtic lettering apart from other styles, which may not emphasize such detailed patterns. For instance, simpler forms or styles that focus on minimalism tend to prioritize legibility and clarity over decorative complexity, while the use of bright colors can be found in various lettering systems but does not exclusively define Celtic lettering. Thus, the intricate knotwork is a defining feature that embodies the richness and tradition of Celtic artistry, making it the correct answer in identifying what sets it apart from other lettering styles.