at= used for saying what destination you are at. For example, you could say "I am staying in my friend's house." but in English you're a lot more likely to say "I am staying at my friend's house." in= similar to 'at' but used for larger locations. You wouldn't say "I live at Manchester." but you would say "I live in Manchester." Also used for when something is inside another thing, like food goes IN the fridge. on= when you are in some way, above something. People can walk ON the ground, but if you were IN the ground you would be dead.

I am sorry Hano0o, but your answet tells little truth. "At" is used to indicate a point or place occupied in space. for example :to stand at the bottom of the barrel. "In" is used to indicate inclusion within space, a place, or limits. for example: walking in the park. "On" is used so as to be or remain supported by or suspended from. for example: Put your package down on the table / Hang your coat on the hook. I hope that helps :D

at: we can use it in >> time & date on: day in: month & season & year & place such as : : at 10:20 pm on Monday in September on September 21st on thursday , september 21 st in 2015