they can be both, all depends where you get them
Christmas lights is series combination
With series Christmas lights, if one burns out, the whole string stops working. With parallel Christmas lights one light burning out only affects that light. This makes it much easier to replace burned out lights in the case of the parallel lights.
Yes, brand high class flashlights have their series curcuits. The special cercuit can be special function. Such as imalent flashlights mainly are touch screen flashlights.
Cheap Christmas tree lights.
They are parallel, or at least you HOPE they are parallel.
Christmas tree lights. LIGHTS for Christmas do not need to in series but conveniently in series saves power. A regulator while usually is in series does not be in series to regulate. FINALLY everything eventually are connected in series. from 475kv transmission to the local home device.
Christmas tree lights and computer cables are also connected in series.
Christmas tree lights and computer cables are also connected in series.
both
Because if one light burns out, all the lights will go out.
Yes
House lights are wired in parallel. If they were in series, when one burned out, all would. Christmas lights are wired in a combination of series and parallel - roughly 50 lights in each series string. that's why if one bulb burns out, a section of the lights goes out.