In the old display systems, the functional element of the display size was also measured. For example, shortening the length of a candle is direct indicator of elapsed time.
The information displayed is obtained by analogy with the information produced by the physical phenomenon, hence the term analogue. In sundials you begin to have the concept of the dial, or a panel equipped to highlight the reading time.
With the advent of mechanical clocks, hourglasses already from water to float and indicator pendulum clock, it becomes natural to use the dial hands. The most famous version, two or more indicators, generally tapered shape / stretched, rotating on a scale in which are engraved the signs of hours, minutes and seconds. Hand axes are generally coaxial, but not always. In wrist chronographs are often lower quadrants within the main dial.
Exist or have existed in systems other than their usual hands. In the early watches had used a single needle and fractions of hours could be deduced from the position of the notches between two consecutive hours. Clocks are used in other hands in a circle whose end does not rotate but moves back and forth along an arc. Also of the clock controller that has the characteristic mark of hours, minutes and seconds on each quadrant independently.
Some models of watches suitable for blind people have opened the lid of the dial so that the reading time can be made to the touch.
All those are digital clock display mode that occurs from discrete values. While the hands forward imperceptibly seamlessly, a digital clock shows a specific time and at one point passes to the next shooting. This method is perfectly suited to the generation that watches the time signal is already digital, such as in quartz watches.
This category covers a very diverse range of techniques, usually the time is shown directly in the form of figures, but there are also very imaginative alternatives (an example is given dall’Orologio Berlin). Moreover, in some cases the time is displayed directly to the user, but is transmitted in digital form to a microprocessor.
This is the case of clocks built into computers, VCRs and other consumer electronics devices.