It offers an attractive price-performance trade-off to the industry’s product. The better the relative value of the substitute, the tighter is the lid on an industry’s profit potential. For example, conventional providers of long-distance telephone service have suffered from the advent of inexpensive internet-based phone services such as Vonage and Skype. Similarly, video rental outlets are struggling with the emergence of cable and satellite video-on-demand services, online video rental services such as Netflix, and the rise of internet video sites like Google’s YouTube.