when you say "it's raining", what is "it" 
@lynnesbian like that saying
The rain in the rain rains mostly in the rain
@lynnesbian the earth
@lynnesbian feel free to say "Q ur dumb" if you weren't asking seriously, but the "it" is called a dummy subject. it's there because English requires a noun of some type to be the subject of the sentence, it doesn't mean anything in particular
@saltqueer i do actually know that, my wife is an amateur linguist and she tells me stuff like that all the time
it's just something interesting and kind of a thought provoking question without an immediately obvious answer
but thanks for the explanation c:
@lynnesbian aaaa i studied linguistics for the like... year I was in university. it's a good subject!
@lynnesbian The rain monster duh
@lynnesbian the local geographic area? The sky maybe? god?
@lynnesbian oh wow. There's a whole Stack Exchange Q/A on this:
https://english.stackexchange.com/questions/5758/what-does-it-refer-to-in-its-raining#5763
@lynnesbian the rain