understanding tilemaps

I am new user to Construct 2. I'm having trouble understanding what tilemaps are supposed to accomplish. My understanding of a tile map is that in a 2D game there is a graphics layer and a tile layer. The tile layer controls movement, can hold events, etc. However, this does not seem to be what a tile map does in Construct 2. I read through the manual entries but I still cannot wrap my head about what its purpose is.   

In plain English, what is a tile map supposed to do?

If you can't think of a use for it in your game, chances are you don't need to use it, it is an optimized way to display same sized tiles...

Its just a different way to use tiled backgrounds sometimes more suitable than standard tiled backgrounds, sometimes not, perfectly possible to make any game without it...