Invincibility frames
Also said as I-frames, Mercy invincibility
A brief window in which you cannot be hurt. After taking damage it stops one mistake killing you twice. On a dodge, it is what makes rolling through an attack possible.
Without them, one touch in a crowd can drain a whole health bar in a blink. Players read the flicker that signals them without being taught.
Say it
“After a hit, give the player 1.2 s of invincibility and blink the sprite at 15 Hz so it is clear they are safe.”
Where you’ve seen it
Dark Souls gives its roll i-frames, which is why rolling into an attack beats rolling away from it. Mega Man flashes after a hit and passes through enemies.
Not to be confused with hit stop
Hit stop stops the action on impact. I-frames let the action carry on while you are safe.