"If good brands don't communicate exactly what the company does up front, they quickly make themselves synonymous with those products or services. Geico, for example, immediately triggers the thought of "insurance." The brand is so strong, they've even tied a gecko to the notion of insurance."
"Weak brands, on the other hand, are forgettable and seemingly unrelated to the company's mission. If people you know are constantly asking "what is it you do again?" you have failed to establish a strong brand. Part of the problem here is disseminating your message, but you have to work the advertising to properly build your brand. Otherwise, it's just wasted dollars."