Tartans are designed by creating a specific sequence of colored threads, known as a sett, which is arranged and then repeated in both directions during the weaving process. Designers choose the colors, stripe widths, and order of the threads to form a balanced and recognizable pattern, often using symmetry or near-symmetry to ensure consistency across the fabric. The design can reflect tradition, represent a group or organization, or simply be created for aesthetic purposes. Once established, the sett defines how the tartan will appear when woven and used in garments like kilts.