Preserving / Stabilising & Stopping
Some like it Dry, Some like it Sweet. A lot of people like it somewhere in between there. Using a Hydrometer, you can check when your wine is at the place you want it to stay. Your yeast will just carry on consuming sugar and producing alcohol until either the sugar runs out, the alcohol level exceeds it's tolerance or some other factor impedes it's ability to continue.
Sodium Metabisulphite or Campen Tablets can help stop and preserve a wine and are often used in conjunction with Fermentation Stopper to ensure the wine remains stable. Use of these chemicals means that the product you bottle will be largely the same (except normal ageing effects) when you open it up, even if you leave it a long time in the bottle. Wine which has not been properly stabilised could recarbonate, causing it to be fizzy or pop it's cork or go dry.
On the other hand, a properly stabilised Wine (or beer, but this isn't really done) will not carbonate so such chemicals cannot be used for natrually sparkling drinks.