How often / when do I need to do safety and emissions test on my car?

I was wondering how often / when do I need to do safety and emissions test on my car? I live in Ontario, Canada. And what do I need to do in order to renew my plates?|||oooh idk about in canada, but where i live/georgia, in order to renew ur license plate, u have to get an emissions test and pass it. They say u should get an emissions test every year!