The word "television", derived from its Greek (tele: distant) and Latin (visio: sight) roots, can literally be interpreted as sight from a distance. Very simply put, it works in this way: through a sophisticated system of electronics, television provides the capability of converting an image (focused on a special photoconductive platewithin a camera) into electronic impulses, which can be sent through a wire or cable. These impulses, when fed into a receiver (television set), can then be electronically reconstituted into that same image. 

    Television is more than just an electronic system, however. It is a means of expression, as well as a vehicle for

communication, and as such becomes a powerful tool for reaching other human beings. 

    The field of television can be divided into two categories 

determined by its means of transmission. First, there is broadcast television, which reaches the masses through broad-based airwave transmission of television signals. Second, there is nonbroadcast television, which provides for the needs of individuals or specific interest groups through controlled transmission techniques. 

    Traditionally, television has been a medium of the masses. We are most familiar with broadcast television because it has been with us for about thirty-seven years in a form similar to what exists today. During those years, it has been controlled, for the most part, by the broadcast networks, ABC, NBC, and CBS, who have been the major purveyors of news, information, and entertainment. These giants of broadcasting have actually 

shaped not only television but our perception of it as well. We have come to look upon the picture tube as a source of entertainment, placing our role in this dynamic medium as the passive viewer.

   电视电视--以快速变化与发展为标志的最普遍、最具有影响力的一项现代技术，正在步入一个极端复杂化与多样化的新时代。 

   这个时代承诺重新塑造我们的生活和我们的世界。 这可以称得上是又一次电子革命，其关键在于电视技术与计算机技术的结合。"电视"这个词来源于希腊语词根(tele：远)和拉丁语词根(vision：景象)，可以从字面上理解为来自远处的景象。 

   简单说来，电视是以这种方式工作的，通过一个复杂的电子系统，电视能够将一幅 图像(这幅图像被聚焦在一部摄像机内的一块特殊的光导底片上)转换成能经过导线或电缆发送出去的电子脉冲信号。 

   当这些电子脉冲信号被输入一部接收机(电视机)时，就可以用 电子学的方法把脉冲信号重新恢复成同一幅图像。但是，电视不仅仅是一个电子系统，它还是一种表达工具和传播渠道。 因此，电视成了一个对其他人发生影响的强大工具。电视这 个领域可以根据其发射方式分为两类。 

   第一类为广播电视，通过电视信号的宽带无线电波 发射展现在大众面前；第二类为非广播电视，使用受控的发射技术来满足个人以及某些特殊利益群体的需要。电视早已成为大众媒介。我们熟悉广播电视，因为广播电视已经以类似 目前的方式存在了大约 37 年。 

   在那些年头中，电视绝大部分一直由 ABC、NBC、CBS 这 些广播电视公司控制着，这些广播电视公司一直是新闻、信息和娱乐的主要提供者。这些广播业的巨头实际上不仅塑造了电视，而且也塑造了我们对电视的理解。我们渐渐把显像 管看作是娱乐的来源，让自己成为这个生动的媒介的被动观众。