Whether a character dodges a hit is determined by their chance to dodge, which is capped at 75%. Dodge is rolled randomly each time the character would be hit. On a successful dodge, the character does not take the hit. For this reason, dodge is handled before block and avoidance, both of which provide a chance to mitigate the damage of hits rather than preventing them outright. Dodge is not affected by the enemy's accuracy.
Sources of dodge
|Acrobatics||Modifiers to Chance to Suppress Spell Damage instead apply to Chance to Dodge Spell Hits at 50% of their value|
Maximum Chance to Dodge Spell Hits is 75% 
Before version 3.16.0, the game had both attack dodge and spell dodge. The former is removed entirely, while the latter became a special stat only obtainable from the Acrobatics keystone. On a related note, GGG has also introduced a new layer of damage mitigation called spell suppression, which has a chance to reduce spell damage by 50% at base value.
For a detailed explanation of these changes, see Version 3.16.0 § Core Character Defences and Recovery.