Lux is the unit in which the light level is measured. It can be very different! For example, at full moon, when the sky is clear, the illumination index will be 0.27 lux, and at bright noon-130 thousand lux (Lux).
Why know the level of illumination? There is a corresponding SNIP, which states that in the workplace in the office, the level of artificial lighting should be from 200 to 300 lux. Otherwise, people will feel uncomfortable, their performance will drop, and their eyes will get tired quickly.
It is also very important to adhere to the lighting standards in hospitals, educational and children's institutions, research centers, libraries, and museums. It is in order to withstand the norms of the SNIP and provide comfort in such public, working rooms that the lux meter is simply necessary.