Advertising and non-advertising folks alike use the word regularly. Like, love, we don't bother to define it. We simply use the word as we do many words -- we have all grown up with an intuitive understanding of what it means, and what we mean when we use it. We use it in reference to companies, products, and even people. But ask someone to define "brand" and you get a deep and confident inhale followed by a few words of preamble, starting with one that indicates the coming statement will be replete with logic and certitude, and continuing with a few words that restates the question as a declaration, "Well, brand is a…" quickly followed by some sputtering that ends up in a verbal morass of conflicting descriptions.
It's not really important to define what a brand is before discussing what it means to create a brand strategy. The difficulty is that "brand" is something that we understand deep within the lineaments of our souls, but is defined in the same way Justice Stewart defined obscenity -- "I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it." Definitions are legion. Heidi Cohen, marketing expert and adjunct professor at NYU, once listed 30 different definitions of branding.
Ultimately, to develop a solid brand strategy, it's more important to define what a brand is supposed to do, than what branding actually is.