Air cargo, commonly known as air freight, is collected by firms from shippers and delivered to customers. Aircraft were first used for carrying mail as cargo in 1911. Eventually manufacturers started designing aircraft for other types of freight as well.
A consumer is  a person or organization that uses economic services or commodities. In economic systems consumers are utilities expressed in the decision to trade or not.
Quick Answer. Primary consumers are animals that eat producers, and since producers are almost always green plants, primary consumers can most simply be defined as herbivores, such as cows and deer. Consumer and producer, in this usage, refer to the production and consumption of energy in a form that can be used for life processes.