Why do geographers divide the world into regions?

Answer 1

The planet is a big big place. It much easier to study and understand it if it is broken down into more manageable bits. Its much easier to deal with just tropical regions or arctic regions alone that the whole planet at one time. And it helps to have geographers that specialize in different regions so that we all can have a better understanding of each one.

Of course cultural geographers have even more regions to deal with.

Answer 2

The world is divided into Time Zones which is because the earth rotates and not every part is in the sun at the same time. As such day/night differs and the time zones allow each area to set their clocks according to the suns position relative to them.

Answer 3

Because the world is too big a thing to understand all at once.