Getting the right goods to the right markets in response to or anticipation of consumer demand is the key function of marketing. Unlike selling which is primarily concerned with the needs of the seller, marketing is primarily concerned with the needs of the buyer. The relationship between buyer and seller is not, however, an entirely random process. Consumers are able to exert a degree of sovereignty over what they buy but producers and sellers can help to fashion that demand by monitoring consumption patterns through time and over space, and in focusing demand on images, lifestyles and products through advertising and special promotions. The processes which link the investigation of the characteristics of the market with production, distribution, sales and after-sales service is termed the 'marketing channel'.