Mineral water is water containing minerals or other dissolved substances that alter its taste or give it therapeutic value. Salts, sulfur compounds, and gases are among the substances that can be dissolved in the water. Mineral water can often be effervescent (or "sparkling"). Mineral water can be prepared or can be obtained from naturally occurring mineral springs. In many places, mineral water is often colloquially used to mean carbonated water, which is usually carbonated mineral water, as opposed to tap water.