What is meant by a zero-watt bulb? Why is it called a zero-watt despite consuming some amount of electricity?

Since childhood, we have always been hearing about a bulb, which we know as the zero-watt bulb installed in almost everyone's house. These low-intensity bulbs can usually be seen in many parts of the house, such as around photo frames or paintings, around religious parts, around showcases, in the bedrooms as night lamps, or even in the garden. In this way, these zero-watt bulbs have become a part of our daily life even today and are making their presence felt. But do you know how this bulb got its name as Zero Watt bulb and why everyone started calling it by this name? 

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But now the most important question here is that why would any electrical device operate at zero watts, at least it would certainly consume some amount of power to run? Even a small LED indicator consumes some power, even if it is a fraction of a watt. Even ''zero-watt'' bulb is, in fact, a 15-watt bulb, then for which reason, it is called a zero-watt bulb despite consuming some amount of electricity? 

So the straight reason for this is that until a few years back, the older electromagnetic meters we used to have for decades were analog and analog meters did not record consumption if the load was very small. This resulted in an inaccuracy in the measurement of power consumption, and instead of consuming some power, it just read 'zero power'. The indicator did not move when the load was only 15 watts with no electrical load other than the "zero watt" lamp at night. Even though that zero-watt bulb was actually 10 watts or 15 watts, people still saw no movement of the indicator in the meter, as the reading was displayed only after some large consumption.

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So this misconception had become in the minds of people that this bulb consumes zero watts of electricity, leading to less amount of bill and this is where the story of the zero watt bulb started. Over time, this term became quite popular in India, which is mostly used by our parents and we also use it sometimes when the zero watt bulb is to be turned on at night.