Question: The programs work on monitors day in and day out for near untraceable period to time. What is the best position to keep the monitor?

Answer: 
The US Government's Occupational Safety & Health Administration (OSHA) provides [ergonomic recommendations for computer monitors](https://www.osha.gov/SLTC/etools/computerworkstations/components_monitors.html). There are a number of factors to consider, especially:

Monitor distance:

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> Sit at a comfortable distance from the monitor where you can easily read all text with your head and torso in an upright posture and your back supported by your chair. Generally, the preferred viewing distance is between 20 and 40 inches (50 and 100 cm) from the eye to the front surface of the computer screen.
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Monitor height:

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> The top of the monitor should be at or slightly below eye level. The center of the computer monitor should normally be located 15 to 20 degrees below horizontal eye level.
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I consider it obvious that human body is made for movement and human vision for relatively long-distance seeing. Thus, I infer that:

**a)** the best position for a monitor is one which is changing over periods of time. 

In this respect (at least) a laptop is ergonomic because it allows you to change its position easily. E.g. you could work one hour sitting, then one hour standing and so on. 

Another, less flexible option is to use a "monitor arm". The arm does not allow for frequent change of the position of the screen indeed, but it allows you to try different positions of the monitor until you feel comfortable. In the same manner it lets people of different heights place the monitor in the best position for themselves.

**b)** a big screen, with bigger scale of displayed content, viewed at a longer distance is better than the opposite - a small screen, tiny scale and short distance. 

(More about about bigger scale here: <https://superuser.com/questions/698121/bigger-picture-on-a-computer-display>).

Ideally the best screen would be a pocket projector with a perfectly stable image and very high brightness. The problem is that projectors are not bright enough to be usable in a sunny day.