All of us are consumers. We consume things of daily use; we also consume and buy these products according to our needs, preferences and buying power. These can be consumable goods, durable goods, speciality goods or, industrial goods. What we buy, how we buy, where and when we buy, in how much quantity we buy depends on our perception, self concept, social and cultural background and our age and family cycle, our attitudes, beliefs values, motivation, personality, social class and many other factors that are both internal and external to us. While buying, we also consider whether to buy or not to buy and, from which source or seller to buy. In some societies there is a lot of affluence and, these societies can afford to buy in greater quantities and at shorter intervals. In poor societies, the consumer can barely meet his barest needs. The marketer therefore tries to understand the needs of different consumers and having understood his different behaviours which require an in-depth study of their internal and external environment, they formulate their plans for marketing.