What are the differences between それ and あれ, そこ and あそこ?

それ and あれ both mean "that". それ indicates closeness of the thing to the person you are talking to, while あれ suggests that the thing is not close to either of you. そこ and あそこ mean "over there". However, あそこ suggests that it is further away than そこ i.e. そこ is over there, あそこ is way over there.