There are three theories that identify a singular characteristic which defines an base, in addition to an acid. These three acid-base theories are: the Arrhenius Theory, the Bronsted-Lowry Theory, and the Lewis Theory. Click each theory to find out more. This time, focus on the second part of each theory regarding bases.
In addition to these theories, the following chemical equation is used for making bases in general:
Metal Oxide + Water → Base
Metal Oxide + Water → Base
If you got all the acid-base theories down, let's take a look at the properties of bases here.