Damage in Last Epoch can be dealt in two different ways: as a hit, or as damage over time.
A damage over time effect deals damage to a target or area repeatedly over a duration.
The most common sources of damage over time are ailments such as ignite, bleed, and poison, which affect individual targets.
There are also damage over time effects that damage all targets within an area, such as Fire Aura, Tornado, Consecrated Ground, and many more.
Any source of damage that is not damage over time is considered a hit. Most damaging skills include a hit, such as Swipe, Rive, Fireball, Elemental Nova, and Rip Blood.
Hits can be dodged, blocked, or turned into a glancing blow, and there are many other effects that trigger either when you hit something or when you are hit by an enemy.
Damage over time cannot be mitigated by most defense mechanics, except for resistances. Damage over time cannot critically strike and does not trigger on hit effects such as Health Gained On Hit.