What are blackout shades?

As the name implies, blackout shades are designed to literally "blackout" a room by blocking virtually all natural and artificial light from entering through the windows. Light is eliminated because the fabric used on these shades blocks 100% of the light. However, there will still be residual light that comes in around the edges of the shades. When installed correctly, blackout shades can reduce up to 99% of light from entering a room.