________ is the product of acid and base reactions.

Salt is a product of acid and base reactions. When an acid and base react together it forms salt and water. This reaction is called neutralization. 

In this neutralization, The cation of the acid (H⁺)combines with the anion of the base (OH^-) to form water. The compound formed by the cation of the base and the anion of the acid is called salt.

For Example- In the following chemical reaction, HCl is acidic and NaOH is basic in nature. These two compounds react together to form NaCl (salt) and water. Salt NaCl is formed by the cation of the base (Na⁺) and the anion of the acid (OH^-).

$\mathrm{HCl}\left(aq\right) + \mathrm{NaOH}\left(aq\right) \to \mathrm{NaCl}\left(aq\right) + {\mathrm{H}}_2\mathrm{O}\left(l\right)$