What exactly is a top down application/design?

Question

I just want a short explanation which answers my question.

Answer 1

Instead of designing a bunch of pieces and figuring out how to connect them, the idea is to start at the highest level (the top) and define needs and design at that level first, then work down each level, defining the needs and designing the solutions at that level to fulfill the design at the higher level. When you get to the bottom, the job is done. (And is probably better organized and easier to maintain and upgrade)

Answer 2

Try thinking opposite to "Face Up". Basically, it is read and / or created upside down. When travelling North, you read a map face up and when travelling South you read the map "Top Down"