What if I use exterior paint on the interior?

Question

I have some leftover exterior paint and I'm thinking of painting the inside of my garage with it. Is it okay to do that? Please explain.

Answer 1

It's okay to use exterior paint on the interior, but not vice versa. Exterior paint is more weather- and wear-resistant. Won't hurt a thing to use it indoors.

Answer 2

If you are painting the inside of your garage, that technically is not exterior.   Exterior is surface exposed to outside, whether.  

The garage interior is protected against direct sunlight and rain, snow, sleet, etc.  -  Interior paint is except for this application.

Answer 3

If you do this, you will alter reality and it will rain indoors.

Just kidding,  it's fine.