Toughness is one of a character's Core Stats. It is defined as a number between 1 and 32.
Your toughness determines your ability to withstand physical and magical attacks and also affects you maximum HP. Some perks are only available at certain levels of toughness. It is similar to what is called "Vitality" or "Constituion" in other games.
Each point of toughness provides 5 points of Health.
The player starts with 2 Toughness, before race/class/background modifiers.
There are several items and events that can temporarily increase your toughness, but permanent increases are not possible outside of levelling up and permanent transformations.
Several items and events may reduce your toughness: