DoT

Damage over Time - the total damage caused over a set period of time.

The game evenly divides this total in set intervals, typically three seconds unless specified.

Dexterity or casting speed increasing effects can slightly reduce this interval's duration. This leads to skills capable of carrying out one more periodic hit of damage, without weakening the average damage produced periodically.

E.g. if Slash dealt a base of 400 damage, it would be the same as saying 100 damage every 3 seconds for 12 seconds). If the interval was reduced to 2.4 seconds, Slash would deal 500 damage (100 damage every 2.4 seconds for 12 seconds).

Damage over Time is the same as Healing over Time except one deals damage and the other heals health.