An acid-base reaction in which an acid combines with a base to produce salt and water is known as a neutralisation reaction. The pH of the neutralised solution depends upon the acid strength of the reactants and their concentrations. The best way to describe the neutralisation reaction is as follows:
Acid + Base → Salt + Water
When a strong acid reacts with a strong base the resultant salt is neither acidic nor basic in nature i.e. it is neutral. For example when HCl, a strong acid, reacts with NaOH, a strong base, then the resulting salt is sodium chloride and water.
HCl + NaOH → NaCl + H2O