The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its development in 1947 by John Bardeen, Walter Brattain, and William Shockley, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics, and the inventors were jointly awarded the 1956 Nobel Prize in Physics for their achievement.
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電晶體是一種固體半導體器件，可以用於放大、開關、穩壓、訊號調變和許多其他功能。在1947年，由約翰·巴丁、沃爾特·布喇頓和威廉·肖克利所發明。當時巴丁、布喇頓主要發明半導體三極體；肖克利則是發明PN二極體。
電晶體由半導體材料組成，至少有三個端子（稱為極）可以連接外界電路。電晶體作為一種可變開關，基於輸入的電壓，控制流出的電流，因此電晶體可做為電流的開關。相較於繼電器或其他機械開關，電晶體由於利用電訊號來控制，開關速度可以比機械開關快很多，在實驗室中的切換速度可達100GHz以上。
電晶體輸出信號的功率可以大於輸入信號的功率，因此電晶體可以作為電子放大器，有許多市售的分立電晶體，但積體電路中的電晶體數量遠大於分立電晶體的數量。例如超大規模積體電路（VLSI）其中至少有一萬個電晶體。
Importance
The transistor is the key active component in practically all modern electronics. Many consider it to be one of the greatest inventions of the 20th century. Its importance in today's society rests on its ability to be mass-produced using a highly automated process (semiconductor device fabrication) that achieves astonishingly low per-transistor costs. The invention of the first transistor at Bell Labs was named an IEEE Milestonein 2009.
Although several companies each produce over a billion individually packaged (known as discrete) transistors every year, the vast majority of transistors are now produced in integrated circuits (often shortened to IC, microchips or simply chips), along with diodes, resistors,capacitors and other electronic components, to produce complete electronic circuits. A logic gate consists of up to about twenty transistors whereas an advanced microprocessor, as of 2009, can use as many as 3 billion transistors (MOSFETs). "About 60 million transistors were built in 2002 ... for [each] man, woman, and child on Earth."
The transistor's low cost, flexibility, and reliability have made it a ubiquitous device. Transistorized mechatronic circuits have replacedelectromechanical devices in controlling appliances and machinery. It is often easier and cheaper to use a standard microcontroller and write acomputer program to carry out a control function than to design an equivalent mechanical control function.
電晶體被認為是現代歷史中最偉大的發明之一，在重要性方面可以與印刷術，汽車和電話等發明相提並論。電晶體實際上是所有現代電器的關鍵主動（active）元件。電晶體在當今社會的重要性主要是因為電晶體可以使用高度自動化的過程進行大規模生產的能力，因而可以不可思議地達到極低的單位成本。
雖然數以百萬計的單體電晶體還在使用，絕大多數的電晶體是和二極體，電阻器，電容器一起被裝配在微晶片（晶片）上以製造完整的電路。類比的或數位的或者這兩者被集成在同一顆晶片上。設計和開發一個複雜晶片的生產成本是相當高的，但是當分攤到通常百萬個生產單位上，每個晶片的價格就是最小的。一個邏輯閘包含20個電晶體，而2012年一個高級的微處理器使用的電晶體數量達14億個。
電晶體的成本，靈活性和可靠性使得其成為非機械任務的通用器件，例如數位計算。在控制電器和機械方面，電晶體電路也正在取代電機設備，因為它通常是更便宜，更有效地僅僅使用標準積體電路並編寫計算機程式來完成同樣的機械任務，使用電子控制，而不是設計一個等效的機械控制。
因為電晶體的低成本和後來的電子計算機，數位化信息的浪潮來到了。由於計算機提供快速的查找、分類和處理數位信息的能力，在信息數位化方面投入了越來越多的精力。今天的許多媒體是通過電子形式發布的，最終通過計算機轉化和呈現為類比形式。受到數位化革命影響的領域包括電視，廣播和報紙。
