Digital distribution (also called content delivery, online distribution, or electronic software distribution (ESD), among others) is the delivery or distribution of media content such as audio, video, software and video games. The term is generally used to describe distribution over an online delivery medium, such as the Internet, thus bypassing physical distribution methods, such as paper, compact discs, and VHS videocassettes. The term online distribution is typically applied to freestanding products; downloadable add-ons for other products are more commonly known as downloadable content. With the advancement of network bandwidth capabilities, online distribution became prominent in the 21st century.