Redesigning applications to make them less sensitive to wide area network (WAN) environments may be impractical; improving underlying WAN characteristics is expensive; and improving only one factor, such as bandwidth, may not appreciably improve application performance. This report, updated by Senior Analyst Eric Siegel, describes cost-effective bandwidth optimization techniques such as compression and caching along with protocol optimization techniques and wide-area file services (WAFS) technologies. Used together or separately, these can improve the performance of applications and file systems by making the WAN characteristics appear to be better than they actually are.