Disjunction introduction or Addition is a valid, simple argument form in logic:

A.

Therefore, A or B.

or in logical operator (sequent) notation:

$A\; \backslash vdash\; A\; \backslash or\; B$

The argument form has one premise, A, and an unrelated proposition, B. From the premise it can be logically concluded that either A or B is true, or both are true.

Here is an example of such an argument:

Democracy is the best system of government.

Therefore democracy is the best system of government or everyone should vote.

Rules of inference