Glass curtain walls refer to non-structural, lightweight outer coverings made of glass, often used on the exterior of buildings to create an aesthetically pleasing and modern look. These walls are primarily composed of glass panels secured by aluminum or steel frames, providing transparency and allowing natural light to enter the building.

Glass curtain walls have a variety of uses and offer a variety of benefits: 

1. Aesthetics: Glass curtain walls give buildings a sleek, modern look and can enhance the overall aesthetic of a building. 

2. Natural light: The transparency of glass allows ample natural light to enter the building, reducing the need for artificial lighting and creating bright and inviting interior spaces.

3. Energy efficiency: Modern glass curtain wall designs are energy efficient, with features such as low-emissivity coatings and thermal insulation that help reduce energy consumption for heating and cooling. 

4. Soundproofing: Although glass curtain walls are transparent, they can also provide effective soundproofing if designed with the proper glass thickness and insulation. 

5. Weatherproofing: Glass curtain walls can withstand the elements such as wind, rain, and snow while still providing a seamless connection between the indoors and outdoors. 

6. Design Flexibility: Glass curtain walls offer a high degree of design flexibility and can be customized in size, shape, color, and glass type to suit architectural style and requirements.

Glass curtain walls are popular in modern architecture because they enable the creation of open, light-filled spaces and promote sustainable design through energy-saving and daylighting strategies. They are often used in commercial buildings, office buildings, shopping malls, and other buildings that require a modern and light-filled aesthetic.