Y2K sunglasses, popularized in the late 1990s and early 2000s, are characterized by their futuristic and bold designs. They often feature sleek, narrow frames in various metallic or brightly colored finishes. The lenses are typically large and may come in unconventional shapes like ovals or rectangles. Y2K sunglasses are iconic for their association with the millennium's tech-inspired fashion trends, reflecting a blend of retro nostalgia and forward-looking aesthetics.