This chapter begins by describing the decorative use of glass. Because of its fluidity when hot, glass can be blown, twisted, and wound into an infinite array of shapes. Using transition metals, rare earth elements, and colloids glass can be made in a rainbow of colors. But glass is not just for the artistic. As lenses, glass has opened up the exploration of both the microscopic and macroscopic worlds. Microscopes and telescopes require glasses of high purity and transparency. But one application, above all others, that relies on glass with unparalleled transparency is as optical fibers. With an innovative approach to making glass fibers, we now have a fiber-based network that spans the world.