In the first place, it is essential to understand both, what a brand is and the universe of significance awoken every time we talk about them. Since the intention here is not to arrive to an hermetic definition, we will try to open the picture to place the reader in a framework that addresses some of the many and diverse approaches have been developed in this regard.
So what do we mean when we talk about brands? As a first approximation, we will begin by consulting the definition of the Spanish Royal Academy :
brand. (From Lat. brand, and of the Germ. *mark, border territory).
1. Signal made in a person, animal or thing, to distinguish it from another, or denoting quality or belonging.
5. Instrument that identifies a brand or something to differentiate it from others, or to denote quality, weight or size.
10. Any fixed point and very characteristic of the coast, alone or combined with other leading line serves as a way of knowing the status of the ship and run its course as appropriate under any circumstances.
«Nowadays we call them logos. But they are symbols of what lies beneath»–Wally Olins.
As defined by the Spanish Royal Academy, a brand is a sign which is made. From this, we draw two key ideas: (1) a brand operates as an index, marking, indicating the existence of ‘something else’; and (2) a brand is a construction.
From the semiotic point of view, Charles Sanders Peirce defined index as «a sign … that refers to its object not so much because it has some resemblance or analogy with it, or because it is associated with the general character it has, as it is in dynamic connection (including the space there) with the individual object on the one hand, and with the senses or memory of the person it serves as a sign on the other. […] The indices can be distinguished from other signs … by three characteristics: first, they hold no significant similarity to their objects, secondly, they refer to individuals, unique units, unique collections of units, or continuous singular; third, they draw attention to their objects by blind impulse.”
This applies, for example, in the case of a person who sees smoke, and immediately associates it with ‘fire’. This person has not seen the fire, and has no certainty of it, but through their experience and what has been apprehended, whenever there is smoke, there is fire. So when you see smoke, a method of induction  works out and concludes: there is fire.
Now, what do brands have to do with the index of Peirce? Firstly, it is vital to recognize brands as signs. Sometimes the term ‘brand’ is used only to refer to the graphic sign used as a ‘mark’ or distinctive ‘signature’ . But when it comes to brands, we cannot ignore the symbolic and discursive universe that is built around them. That’s why brands work as indices that point, suggest and indicate ‘what lies beneath’: their personality, attributes, values, promises, their «soul», essence, identity.
Moreover, the meaning attributed to a brand -as every linguistic sign-, is not given beforehand but as the result of a construction. The process of signification in which it is involved is active, continuous and dynamic, because it involves a interlocutor, with whom the brand negotiates the meaning to be granted at a certain time and place.
It is Leonor Arfuch who states that «there is a tension between the meaning that the speaker intends and appropriation made by the recipient».  As a result, developing an active, ongoing process of signification, in which both the enunciator (in this case, the brand) and recipient are partners in a continuous flow of meaning that is negotiated and re-pacted as long as the conversation takes place.
 Peirce, Ch.S. “Ecrits sur le signe”. Paris, Seuil, 1978.
 The inductive method is used to draw general conclusions from particular premises.
 Klein, N. “No logo”. Barcelona, Paidós, 2001.
 Arfuch, L. “Design and communication. Theories and critical approaches”. Buenos Aires, Paidós, 1997.