looksee wrote: » In your example it is 'affect all devices' and 'the changes will take effect'. How to come up with a simple way of remembering I am not sure. It is made more complicated as the words have meanings that sneak very close to each other. You really are not stupid. Somehow I know exactly how to use the two words correctly, but I am struggling to come up with a reasonable explanation - both can be used as both nouns and verbs, and sometimes if you restructure the sentence you use the other one - for example The work will affect all devices The work will have an effect on all devices. I will let someone else do the grammatical stuff!