$NaNO_3$, also known as sodium nitrate, is an ionic compound composed of sodium (Na+) and nitrate (NO3-) ions. It is a colorless, crystalline solid that is commonly used in various industrial and agricultural applications, as well as in some food preservatives. $NaNO_3$ is an important compound in the context of classifying chemical reactions, as it can participate in a variety of chemical reactions, including acid-base reactions, redox reactions, and precipitation reactions.