Over the years, the hi-tech industry has come up with a diverse assortment of solutions to optimize bandwidth utilization in all its forms. Most of these technologies are targeted to answer a specific need, while a combination of these technologies is often used in an attempt to deal with new challenges posed by ever more sophisticated technology. The following is a very partial list of the most common solutions available in the marketplace.
 

Caching: Used to store repetitive files to make them available without having to move them across expensive lines. The cache servers store the frequent content and serve it directly to the user, instead of requesting it from the original server. Cache servers emerged from standard web caching and evolved into peer-to-peer caching. Caching can be legally applied only to cacheable traffic, as defined by the content owner. Since content owners want to control the availability, quality and monetization of their content, most content is defined as non-cacheable.

Compression: Applied in a lossless manner, in which content is de-compressed on the receiving side, or in a lossy mode. This solution is typically used in limited bandwidth links for multimedia content. Compression consumes significant computational resources on both sides of the line and, naturally, can be losslessly applied only on compressible traffic. In the modern web most traffic, with the exception of text-based types such as HTML, cannot be compressed.

Blocking: A very effective way of managing overzealous bandwidth usage is by preventing sessions from being created. This is typically done on a protocol basis. However, it is not recommended for service providers, as it significantly impacts customer satisfaction. Recently, some service providers suffered very bad PR and churn rates due to blocking, while others were hit with significant penalties. 

Traffic Capping, Shaping and Throttling: Many service providers implement bandwidth capping and other solutions as a means to limit the amount of available bandwidth. Bandwidth caps are typically applied when a line becomes overloaded. Traffic can be capped on a general level, but mostly it is applied to certain protocols (mainly peer-to-peer). This is a general solution to the problem of overloaded lines. As such, it can result in a number of issues, mainly a drop in the quality of experience, as well as legal exposure. 

Protocol Acceleration: TCP/IP and HTTP were designed decades ago, in an effort to provide reasonable utilization over all media. And indeed, they still hold. Nevertheless, in extreme cases - high-latency satellite links and fluctuating wireless medium - these standard protocols provide poor bandwidth utilization. Commercial systems were developed to provide a modified medium-dependent optimized protocol. Such protocols accelerate traffic over available links, yet do not reduce traffic volume (apart from insignificant header compression).