Why is north usually at the top of maps?
The short answer
Putting north at the top is not a rule imposed by Earth. It is a convention that became widespread and makes maps easier to compare and discuss.
There is no natural “up” on a map
From space, Earth has no absolute top or bottom. Historical maps have placed south at the top or emphasized a particular city or religious center.
Why a shared orientation helps
When many people use the same orientation, it becomes easier to compare places and describe routes. North-up is one shared symbol system that helps map readers communicate.