After a wine is done fermenting, the amount of sugar that remains is called “Residual Sugar” (sometimes abbreviated RS). This determines how sweet the wine is going to be. Residual sugar is found in all wine. As a general guide, if the wine has less than 2.5% RS it is a dry wine and sweet wines have greater than 2.5% RS. In other words, the greater the percentage of RS, the sweeter the wine. As an example I was recently at a tasting where the house Reisling was listed at 6% RS.
The level of RS can occur naturally in the winemaking process but is often manipulated by the winemaker. The course of fermentation can be stopped early before all of the sugar converts to alcohol or the winemaker can choose to add more RS later.
To all of our American readers have a safe and relaxing 4th!