Toughness

Toughness is a Fallout, Fallout 2, Fallout 3, Fallout Tactics, and Van Buren perk.

Fallout, Fallout 2 and Fallout Tactics
When you are tough, you take less damage. Each level of this perk adds +10% to your general damage resistance.

Fallout 3
With the Toughness perk, you gain +10% to overall Damage Resistance, up to the maximum of 85%. You will also gain a unique dialogue option when talking to Ted Strayer during the You Gotta Shoot 'Em in the Head quest.

Van Buren
Even tougher than the old Toughness! No longer just bullets and punches, now you can resist fire, plasma, and grenades!

Behind the scenes
The image of this perk is a reference to Superman.