When union members who have a dispute with a company walk around outside the firm's place of business carrying signs and talking to the media and public about their concerns, they are using a tactic known as

Picketing

Explanation: Picketing is simply an act of a non violent protest or strike by disgruntled workers aimed towards the decision and policy makers. The workers usually hold placards with written words about their dissatisfaction in their work place. Picketing could occur if the workers feels the management are taking undue advantage of them; increasing working hours and decreasing wages, unfavorable working conditions, fighting for increment of wages etc. Picketing are legal if done in accordance with the law.

So the union members having disagreement with the company were using the Picketing tactics

is this supposed to be a question