All good Christmas tree lights are in parallel so if one bulb fails all the others still work. Series circuits are however easier and often cheaper to make as less materials are required.
They are or were wired in series, one goes, they all go.
series
Always parallel. Homes should never be wired in series. (That would be like the old Christmas tree lights where, if one bulb burned out, the entire string would not light up.)
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.
it would be kind of both
Everything in a house is wired in parallel. If you had lights is series when one burns out they would all go out, much like cheap Christmas lights.
its a series connection
They are parallel, or at least you HOPE they are parallel.
Cheap Christmas tree lights.
Miniature Christmas tree lights are typically wired in parallel. This means that each light has its own individual connection to the power source, allowing the other lights to remain lit if one bulb burns out. The wires are connected to a central power source with fuses to protect against overloading.
voltage drop across all the parallel elements is equal and it is equal to input voltage. we know for home applications in voltage and frequency is fixed, ex: in India voltage=230v and frequency=50 Hz. All devices we used in home having voltage specification =230 to 240v, but different current. so home use parallel circuits. To make this a bit more general, in a series circuit each device in the circuit has some dependence on all the other items. A simple example is a number of light bulbs in series. If any one light bulb burns out the circuit opens and all the other bulbs go out. Also if you needed to add more bulbs in the same series circuit then all bulbs would be dimmer.
Christmas tree lights and computer cables are also connected in series.