How do u define an urge?

I want to understand what is considered as a urge as everyone will have there own definition and experience, for a long time i didn't think i was addicted to porn so i never noticed my urges i just counted them as my habit. Now that i am trying to reboot, i am missing porn i don't look for it because i know i'm rebooting is this an urge or is it something stronger, i get sensations like how it used to feel to masturbate, and i get hard erections from slightest touch of cloths or anything. Even when i have to pee i feel pressure in the balls. I don't count all these physical events as urges! How would you define your urge from mild to severe, so that i could understand better!