Mod group (mod family) prevents other modifiers from the same family to be randomly generated on the same entity.

the item level, monster level, area level), and for items only raises the item's level requirement to 80% of it's value

Mod level governs the minimum required level of the entity for a modifier to appear (i.e.

mod generation type determines how the modifier is generated, for example whether it's a prefix, suffix, corrupted or always applied (like on unique items).

Mod domain governs the type of entity the modifier is going to appear and may confer some specific rules (such as the number of affixes).

Modifier generation is gated by specific conditions that govern if and how likely a modifier is going to appear:

Some specific circumstances like the rarity of a monster, being touched or possessed by a Tormented Spirit, etc can also apply modifiers innately without them being randomly generated.

Modifiers can either be innately applied (as 'implicit' modifier) to entities, be granted under specific conditions or randomly generated. In particular area and monster effects may be hidden from the player. On the wiki, some of these effects have a custom text specific to the wiki and are noted with (HIDDEN) in the description. Since not all statistics have a visible text, it is possible that some effects are granted by the modifier but are not visible to the player. Modifiers are specific to items, monsters, strongboxes or areas. A modifier applies statistics, a buff or grants a skill to an entity.

Caster of magic mod