Understanding consumers has become the focus of much attention in the marketing world because the driven force behind the market is the consumer. However, Kolter (1996) claims that when choosing products and services, consumers are often influenced by several factors such as attitudes or behaviour. Clearly, to sell products successfully, marketers need to understand and target the specific groups interested in their products. In the literature, many researchers claim that consumers attitudes predict their purchasing behaviour. However, some authors believe that behaviour should be measured in order to predict buying behaviour. This essay will argue that attitude is the major influence in a buyers purchasing decision. Firstly, the report will show how consumers attitudes influence behaviour, using high or low involvement products as an example. Secondly, another major factor influencing buyers attitudes or behaviour, brand loyalty will be analysed. Finally, the role of advertising in influencing future purchasing decisions will be discussed