Picket

To object publicly, on or adjacent to the employer's premises, to an employer's labor practices, goods or services. The most common form of picketing is patrolling with signs.

To object publicly, on or adjacent to the premises of a business, to a business' labor practices, goods or services.

To surround the entrance of a business and encourage patrons and managers to boycott the employer or to otherwise negatively call attention to the business.

The most common form of picketing is patrolling with signs.

Picket lines have no legal basis and are merely PR gestures. But a strong tradition exists not to cross a picket line and on that basis, they can be powerful tools.