Ask HN: How Google Maps works?

I have an idea for a website that requires to implement a zoomable/pannable interactive map, similar to Google Maps but without all the bells and whistles. The map itself is for a fictitious place, so I really need to create it from scratch.

I don't have much experience in Javascript or in maps creation, so I would be grateful if you could point me to the right direction.

In particular:

1. How the maps are normally represented? I bet they are vector-based rather than raster images for different zoom levels. Is there a common format or any standards for storing the maps? I don't need anything complex, just a schematic representation of terrain.

2. Are there examples of how to implement panning/zooming with Javascript?

I will appreciate any tips, from links to Wikipedia and blog posts covering this, to search terms that will lead me to them.

Thank you!