The opposite of an acid is a base, and that's exactly what an antacid is. Antacids make you feel better by increasing the pH balance in your stomach. The pH system is a scale for measuring the acidity or alkalinity of a given environment (in this case, your stomach). The scale goes from 0 to 14. A pH of 7 is neutral. Below 7 is acid. Above 7 is alkaline.
Economy is the large set of inter-related economic production and consumption activities which aid in determining how scarce resources are allocated.
For the most part, the United States has a market economy in which individual producers and consumers determine the kinds of goods and services produced and the prices of those products. The most basic economic institution in market economies is the system of markets in which goods and services are bought and sold.