The wild yeast or contaminants naturally present on fruits will produce a fermentation of low quality. These are chemicals which permit the yeast population to increase and thereby produce a vigorous fermentation. Grape juice is unusually adequate nutritionally - a good reason for its tradition as a wine fruit. Other fruits and honey may require added nutrients to achieve a proper fermentation. This chemical has important preservative action when used in small amounts.
Kits supply the needed dosage in easily dispensable form as bisulfites.
With ideal sanitary conditions the use of sulfur dioxide can be reduced or eliminated. A little goes a long way and it should not be overused. A small plastic hose is useful for removing the wine from the sediment at the completion of the fermentation and during other finishing steps. Contrary to tradition, cork stoppers and aging in wooden casks are not essential in wine making, particularly for the beginner. While you may expand into such practices, it is best to start simply.