The sediment or solid matter in wine is called "lees."
Sediment is often found in aged wines (red) that have been bottled for many years. This is because substances such as tannins in the wine combine with molecules to form solids over time.
It may feel rough in your mouth, but it is generally not harmful to your body.
In the case of vintage red wine, in order to prevent sediment from entering the glass, the wine is sometimes transferred from the bottle to a container such as a decanter, leaving the sediment in the bottle. This is called decanting .
