I am a custom picture framer. This article really doesn't tell the whole story about the types of glass available. The key function of glass over paper or fabric artwork is to protect it from moisture, bugs, dust, smoke, or what have you. However, glazing can harm a work of art if it is allowed to rest directly on the photo, painting, print, poster. Buy a mat or ask your framer to install glass spacers.
Types of glazing: Regular clear: no UV protection or reflection control, inexpensive.
Conservation glass: UV protection, no reflection control, mid-range cost.
Reflection control: Old school, fuzzy, stuff is the old technology. Ask for Tru-Vue Anti Reflective glass. It cuts the glare without compromising the image quality. It is higher cost, and requires special cleaning. It has about 80 percent UV protection.
Museum glass: Amazing stuff! Reduces glare and has 100 percent UV protection. Expensive, but worth it in terms of protecting and enjoying your photos and artwork.
Also, a word on acrylic: If you are dealing with framer's grade, there is no compromise on the image quality at all; it is as clear as glass with a fraction of the weight and does not pose the danger of breaking. Great choice when shipping something or for art hanging in a child's room.
All light fades your artwork and photos, not just direct sunlight. Protect it and enjoy it for generations.