Acidity is the level of acid in your wine. The higher the acidity, the more sour or tart it will taste. 

Fruits such as lemons and strawberries have high levels of acidity, while bananas have lower amounts. Wine falls between coffee and lemonade. 

White wines and sweet wines have higher acidity, while red wines have lower acidity. On top of giving some wines their refreshing qualities, high acidity gives some wines more aging potential.