Insulated glass units (IGUs) are windows made of two or more glass panes separated by a space filled with air or gas, such as argon or krypton. This design helps reduce heat transfer, making buildings more energy-efficient. IGUs are commonly used in residential and commercial construction to improve insulation and comfort. The space between the glass panes is sealed to prevent moisture and air from entering, which helps maintain the unit's performance over time. IGUs can also be customized with various coatings and tints to enhance UV protection and reduce glare, further improving indoor environments.