More than ninety percent of all scientists who have ever lived are alive today. It is the goal of ECHO to record their stories and the ever-expanding, ever-accelerating history of recent science and technology using a contemporary technology well suited to such a daunting yet critical task: the Internet. [...] On its most fundamental level, ECHO provides a centralized guide for those looking for the scattered Web sites on the history of science and technology. Its staff will annotate these sites so that it will become easier for those seeking historical materials to find exactly what they are looking for, or for the merely curious to explore topics of interest. Beyond this important service, ECHO provides tools and subsections of the site for each of its constituents. [self-description]