It is a negation - so anytime you combine it with a verb (grammatically). Ex: I have seen the movie --> I have not seen the movie When combined with the verb

It is a negation - so anytime you combine it with a verb (grammatically). Ex: I have seen the movie --> I have not seen the movie When combined with the verb "do" (and giving a command or instruction) it would negate the verb "do" Ex: Please do run on the lawn --> Please do not run on the lawn