Oops, my bad. A stop is equal to one half the light or twice the light of something.
For instance. 1 stop more is twice the light of something. 1 stop less is half.
This translates into changes in shutter speed, aperture and ISO. The most common change is shutter speed.
If you're correctly exposeing at 1/100 and the the light changes to be brighter by one stop, then the correct shutter speed is 1/200. Conversly, if the light loses a stop, then the correct shutter speed is 1/50.
No, you have it opposite. 1/50 is more light coming in as compared to 1/100. I used 1/100 as the baseline.
If you this image, 1/250 is the correct shutter speed. 1/125 is twice as long of shutter speed, so half as much light is need to expose correctly. 1/500 is twice as quick, so you need twice the light of the original.
Less light = longer shutter speed; more light = shorter shutter speed.