What is the primary purpose of a 'no trespassing' sign?

The primary purpose of a 'no trespassing' sign is to prevent unauthorized entry into an area. These signs serve as a clear legal notification that the property is private and that individuals who do not have permission to enter are subject to legal action or consequences. The presence of such a sign communicates to the public that they are not allowed to enter without permission, thereby reinforcing the property owner’s rights and enhancing security measures.

While informing individuals that they need to leave is an aspect of enforcing the sign's message, the overarching goal is to clearly delineate the boundaries of the property and discourage unauthorized access. Allowing access to specific individuals pertains more to permissions granted rather than the sign's main function of maintaining overall security by restricting entry. Indicating a private event could be a secondary implication but is not the primary function of a no trespassing sign, which is fundamentally about controlling access.