I do celebrate it but the only meaning that I know is from Mean Girls (In the real world, Halloween is when kids dress up in costumes and beg for candy. In Girl World, Halloween is the one day a year when a girl can dress up like a total **** and no other girls can say anything else about it) and the one from the Church that is basically about Satan. There has to be like a story or something. Did your teachers told you something about this holiday?
It's becoming increasingly popular in Australia. It was never a thing when I was a kid (I'm 22) and now my nieces and nephews have all these Halloween parties coming up. My sister is organising trick or treating in her neighbourhood community (she lives in a suburb of Sydney that's basically all young families) and supermarkets are going crazy with Halloween decorations.
10-15 years ago, it was "that's an American thing" and in the past 5 years it's become massive in Australia. I think it's permeated Australian culture through American pop culture (movies, TV shows, cartoons, etc) and kids really want to do it.
It also means people go nightclubbing in costumes, but that's not really a recent thing. I think that's been the case for a while. It's only "trick or treating" that's recently become a thing.
I'm from the US so its obviously big here. But sadly my neighborhood doesn't seem to celebrate it my family usually goes trick or treating but we don't decorate our house
I work in an institute as an English teacher and we decorate the place before Halloween, but just because we explain students it's part of the US culture. People throw Halloween parties and stuff but it isn't a big deal here. If people want to dress as anything they want, we have carnival for that. That's the time of the year when girls can dress like ****s if they want.
It's very big here in the US. I first went to a halloween store in early September to check out what they had I love halloween so I'm glad we actually celebrate it here and go all out
Halloween isn't a thing where I live in Australia, I'm going to a Halloween dress up party but that's more just an cover for lets get drunk and dress up
Halloween has various meanings, such as a ghetto fight at a Denny's. The horrors of the fellow flops that some people make fun of for the last couple of years, and then it becomes religious where some people view it (i.e mostly Christians) as the devil's birthday. Which is utter ******** because it's a holiday of fun and laughter and should not be viewed as a religious-restricted or a satanic holiday. But it's all about fun.
Halloween is not widely celebrated here not as much All Saints' Day and All Souls' Day when everyone goes to cemetery to commemorate their deceased loved ones.
Nothing, people here are XVIII century religious and would demonize everything. It's associated with "american culture" and it's considered childish and ridiculous to celebrate it.
Yet they created that tacky disgusting ripoff Dia de los Muertos thing and literally build death altars to worship the dead at schools and public spaces (and it's no coincidence that it's celebrated right after Halloween on November 1-2)
Canada, so just the same as in the US. As a kid I thought the whole world would walk around and get candy. The streets were always packed. Now there's not that many kids around so it's emptier, but there are tons of Halloween parties with costumes.
The catholic church makes Halloween parties for kids here, giving them candy, but just saying not to dress up as any sort of devil.
The next day is All Saints Day/All Souls Day so my family always goes to a cemetery and light candles even though we don't have any family that has died here in Canada.
my family usually goes trick or treating but we don't decorate our house
I love halloween so I'm glad we actually celebrate it here and go all out 
(and it's no coincidence that it's celebrated right after Halloween on November 1-2)