When alkalis (bases) and acids react together, they form two things:

1. Salt: This is an ionic compound formed from the positive ion of the base and the negative ion of the acid.

2. Water: This is formed from the hydrogen ions (H+) from the acid and the hydroxide ions (OH-) from the base.

This reaction is called neutralization.

For example:

* Sodium hydroxide (NaOH, a base) + Hydrochloric acid (HCl, an acid) → Sodium chloride (NaCl, a salt) + Water (H₂O)