Voice over Internet protocol (VoIP) is a technology that integrates voice services, such as those provided by long distance telephone carriers, into data networks. This Topic in Depth presents information about the development and future of VoIP.
VoIP has received considerable attention in recent years since it blurs the line between telecommunications and Internet. Among other things, it has the potential for enabling virtually free person-to-person communication for anyone with an Internet connection.
Many cities around the world offer subways as a primary mode of public transportation. These subway systems are not only major accomplishments in civil engineering, but have a rich history. This Topic in Depth explores the technology, history, and future of subways.
The Family Asteraceae (a.k.a. Compositae, Composite, Sunflower, Aster) is an impressively large and diverse family of flowering plants (circa 20,000 species). This Topic in Depth offers an assemblage of sites that provide images of, and introductory information about, this remarkable family.
This Topic in Depth explores some of the diseases and other threats, such as gypsy moths, emerald ash borers, and Asian longhorned beetles that certain trees must contend with to remain healthy and vital.
This Topic in Depth discusses the variety of instruments used to collect climate and weather data, from anemometers to thermometers. There is also plenty of information about individual weather stations and data collection initiatives.