A signal is a sign "caused or used specifically to elicit a pre-arranged and agreed-upon reaction, whether in a group or individually, in the form of defined manifestations of human activity."

Signs symbols that "lead men to action, they lead them to do or not do something."

The relationships between signal, sign, and information.

In SIGN, SIGNAL, INFORMATION: the relationships of construction and transfer of meanings , Carlos Xavier de Azevedo Netto summarizes:

Incidentally, any graphic, sound, geological, astronomical, etc. form of signaling is understood, without implying any relation to a possible construction of meaning. The sign is an entity devoid of mechanisms for the construction of meanings, therefore:

By way of example, the specific object of information theory is not signs, but units of transmission that can be quantitatively computed independently of their possible meaning; these units are defined as “SIGNALS”, but not as signs. (ECO, 1980, p. 15)

Umberto Eco

From this perspective, one can relate signals to stimuli, viewing them as unintentional events, both of human and non-human origin, that occur without any intervention from a conventionalization process for the creation of meanings , placing them outside the sphere of the sign.

The signs of semiotics

Semiotics includes the study of signs and sign processes, indication, designation, similarity, analogy, allegory, metonymy, metaphor, symbolism, signification, and communication.