A more thorough explanation:

Picketing is a way of protesting where people stand outside a workplace or organization to bring attention to an issue, often a disagreement between workers and their employer. The goal of picketing is to persuade employees or customers to stop working or doing business with the organization until the issue is resolved. Picketers usually hold signs with messages that explain their concerns.

Picketing is protected by the Constitution as a form of free speech, but it can be regulated to some extent. For example, picketing may be restricted if it is considered unfair or if it causes harm to the organization being picketed.

There are two main types of picketing:

• Primary picketing: This type of picketing takes place at the workplace of the employer with whom the picketers have a dispute. The goal is to put pressure on the employer to resolve the issue.
• Secondary picketing: This type of picketing takes place at the workplace of an employer who is not directly involved in the dispute. The goal is to put pressure on this neutral employer to stop doing business with the primary employer until the issue is resolved.

For example, if workers at a factory are on strike because they believe they are not being paid enough, they may picket outside the factory to bring attention to their cause. This is an example of primary picketing. If the workers also picket outside a store that sells products made by the factory, this is an example of secondary picketing.