When you own shares in a public company—even a single share—you become a part-owner of that business. And part-owners get to vote.

Every year, public companies hold annual meetings where shareholders vote on important decisions. You'll receive proxy materials in the mail or your email, and you'll be asked to weigh in on things like:

• Who sits on the board of directors

• Executive compensation packages

• Whether to approve mergers or acquisitions

• Shareholder proposals on environmental, social, and governance (ESG) issues

That last category is where things get interesting for the values-driven investor.