Hitlag occurs whenever a character hits a target, frames get frozen to give the player a sense of "weight" behind each attack. The amount of hitlag depends on the target hit. Ranged characters and skills aren't affected by hitlag.
Hitlag can effect both buff durations and aura durations. By hitting enemies, we can extend the duration of some effects, such as:
There are some skills, namely deployables, unable to be extended by hitlag, known instances include: