Leather Armor is the lightest, cheapest and least protective body armor which offers an armor class of 8. Since it has +2 penalty against slashing and piercing attacks, it offers no protection against these types of attacks. It's sold at many weapon and armor stores throughout the games. This appears in Icewind Dale.
Leather armor, despite the popular misconception, is not soft and supple like the leather used to make a ranger's boots or a druid's robe. That kind of leather offers no better protection than common clothing.