There are two major terms used for damage in Android: Netrunner. Effects can "do" damage to the Runner or cause the Runner to "suffer" damage. Damage that is dealt to the Runner results in the Runner suffering that damage, but not all damage that is suffered is dealt. Both dealt and suffered damage can be prevented.
"Taking" damage is rarely used, but it is synonymous with suffering damage.
I've been seeing some weird conversations crop up about damage. First off, my understanding is there is a clear difference between "suffering" and "doing" damage. Generally speaking, when the source is from the Runner or if the Runner has a choice in the damage, the Runner will "suffer" damage (examples being or respectively). Otherwise, if the Corp damages the runner directly with a card ability, the damage will be "done" (as in "do # damage"). I hope these generalizations aren't too restricting, but this is the pattern I've seen. Is this (for the most part) a correct way to look at "suffering" and "doing" damage?
Second, I've noticed that "doing" and "suffering" damage are not synonymous. For example, will not add one damage to Tri-Maf Contact being trashed because the damage is "suffered" by the Runner rather than "done" to the Runner. The agenda only deals net damage if the runner "suffers" a brain damage. No Ice currently cause the runner to "suffer" brain damage. Say that you "do 1 brain damage" with . Should Sentinel Defense Program not trigger because the runner did not "suffer" a brain damage? I guess my point for this paragraph is "we know suffering isn't equivalent to doing, but is doing equivalent to suffering"? (not all fingers are thumbs, but all thumbs are fingers) The utility of Sentinel Defense Program is extremely limited if the Runner "suffering" brain damage does not include "doing" brain damage.
Now I'd like to add the term "taking" damage into the mix. What is the difference between "taking" and either "suffering" or "doing" damage? It seems to me the logical thing would be that "taking" damage is the actual act of randomly trashing a card from your hand (or flatlining if you can't resolve "taking" all of the damage). Is this true? The core rules say the following:
"If the Runner takes more damage than the number of cards in his grip, or if he has a maximum hand size of less than zero at the end of his turn, then he is flatlined and the Corporation wins the game."
Note: the following questions might be rendered moot or just trivial based on your answers above!
Is there some sort of order to "suffering/doing" and/or "taking" damage? When you are "done" or "suffer" 4 damage with only 3 cards in hand, do you immediately flatline? Or do you "take" 4 damage which resolves in the ordered fashion the core rule book suggests (Trash cards one by one, then when you go to trash the 4th card, you lose)? At what point do/can you prevent damage? While it's being "done/suffered" or being "taken"? If you prevent the brain damage "taken" from 's subroutine, do you not get to End the Run?