Electronics is that branch of science and technology which makes use of the controlled motion of electrons through different media and vacuum. Today electronics are available all over the place from the highstreet, such as Maplin Electronics, to the Internet such as Amazon. The ability to control electron flow is usually applied to information handling or device control. Electronics is distinct from electrical science and technology, which deals with the generation, distribution, control and application of electrical power. This distinction started around 1906 with the invention by Lee De Forest of the triode, which made electrical amplification possible with a non-mechanical device.
Until 1950 this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers and vacuum tubes. Most electronic devices today use semiconductor components to perform electron control. The study of semiconductor devices and related technology is considered a branch of physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics. More information from Electronics Industry News
Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits.
The number of different analog circuits so far devised is huge, especially because a 'circuit' can be defined as anything from a single component, to systems containing thousands of components.
Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits such as mixers, modulators, Laptop Batteries, etc. Good examples of analog circuits include vacuum tube and transistor amplifiers, operational amplifiers and oscillators.
Digital circuits are electric circuits based on a number of discrete voltage levels. Digital circuits are the most common physical representation of Boolean algebra and are the basis of all digital computers. To most engineers, the terms "digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits. Most digital circuits use two voltage levels labeled "Low"(0) and "High"(1). Often "Low" will be near zero volts and "High" will be at a higher level depending on the supply voltage in use. Ternary (with three states) logic has been studied, and some prototype computers made. More information from UK Electronics Limited and Electronics Jobs & Recruitment @ Electronics UK
Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits. Digital Signal Processors are another example. From ELEKTOR | Electronics: Microcontrollers