This document discusses acids and bases. It defines acids as solutions with excess H+ ions, noting they taste sour and can corrode materials. Common acids include acetic acid in vinegar and citric acid in fruits. Bases are defined as solutions with excess OH- ions and include bases in soaps, ammonia and cleaning products. The document explains properties of acids and bases, such as acids turning litmus paper red and bases turning it blue. It introduces the pH scale for measuring acidity and alkalinity, noting the scale ranges from 0-14 with 7 being neutral. Acid-base reactions form salts and neutralize solutions.