This document provides an overview of acids and bases. It defines acids as compounds with a sour taste that change litmus to red and react with metals and bases. Bases are defined as compounds with a bitter taste that change litmus to blue. The document then discusses three theories that explain acids and bases: Arrhenius theory defines acids as substances that produce H+ ions in water and bases as substances that produce OH- ions. Bronsted-Lowry theory defines acids as proton donors and bases as proton acceptors. Lewis theory defines acids as electron pair acceptors and bases as electron pair donors.