Answer 1

just to lead the way. it describes ways to unterstand and solve a given Problem.
its a theoretically approach where u could identify possible Dead ends or weaknesses within your project

top-down Starts at the end of the whole process and you go all the way down until u reach the bottom. what might be a single function.

bottom-up is the opposite. u Start at the bottom of your project and Plan and Plan your way up to the abstaction layer.