Feb 26
adminEducation
Large, international computer network linking tens of millions of users around the world is called the Internet. It is used daily by many individuals for the main purposes of sending and receiving electronic mail (e-mail), obtaining mountains of information on almost any subject, or to communicate with coworkers on projects. Access to the Internet is obtained only by subscription, and an Internet address is needed to receive a message or to send a message to another Internet user. Such addresses have a specific format that specifies the name of the user, the machine they are working on, and where that machine is located. The Internet began as a network of computers, the Advanced Research Projects Agency Network, or ARPANET, supported by the U.S. Defense Department. The National Science Foundation (NSF) supplied funding to extend the network to connect research-based supercomputers at various sites across the U.S. By the end of the decade, the Internet had extended to connect countries from around the world. The World Wide Web, an application that gathers resources from the Internet into a series of menu pages, or screens. The advent of the World Wide Web is undoubtedly one reason for the explosion of home computer use experienced at the close of the twentieth century.
Feb 05
adminEducation
The most prominent features of the Earth, based primarily on size, are the continents and ocean basins. Plains, plateaus, and mountain ranges are the second most prominent features on the solid parts of the Earth. The continental masses with their major surface features appear to have a high degree of permanence and to be the products of forces that act over extremely long periods of time. Although the term continent generally refers to large and extensive landmasses or main lands, such as continental Europe, it has distinctive meanings in the Earth sciences. Geographically, “continent” refers to the surface of large continuous landmasses that make up about 29.2 percent of the Earth’s surface. These large land areas are: Asia (29.9% of the land area), Africa (20.6 %), North America (14.8%), South America (12%), Antarctica (10.5%), Europe (7 %), and Australia (5.2%).The continents are distributed unevenly over the Earth’s surface. More than 65 percent of all the land area, for example, lies in the Northern Hemisphere, which is sometimes referred to as the “land hemisphere.” The Southern Hemisphere is truly an oceanic realm. Only about 11% of the Southern Hemisphere is above water. The crust of the continents is believed to have originated by a chemical change in which lighter materials from the volcanic basalt of the mantle.
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