Firms can advertise in a lot of ways, such as magazines, posters, billboards and even carrier bags, but one of the main forms of advertising is television.In the modern market place, packaging is very influential in the demand for goods. One example of this is within the entertainment industry - CD quality pirates are available to anyone with a computer and a CD burner and retailers are finding thefts of empty cases (packaging) on the increase because the casing is now the most desirable and most expensive part of many cd based formats. This not only applies to music, but also game consoles as they are very easy to "chip- (modified and cracked to play copied games). A good brand name and can increase the demand for products, take the example of shampoos. Most shampoos use a chemical from ICI, which is the cleaning agent. But because of the brand name and the reputation consumers will often buy the expensive branded products when cheaper ones are available, and in many respects the products are of the same quality.There are some simple assumptions concerning the behaviour of consumers and producers. The theory of consumers demand (how consumers make purchase decisions) assumes that consumers are rational, that is, they want to make the decision that will give them the greatest satisfaction, known as maximising their utility. The optimal choice for a consumer, therefore, is that choice among the available options that will enable him or her to maximise utility. The options available to the consumer are determined by his or her purchasing power (a function of income and access to capital, including credit), and the prices of goods and services available. Given the information available concerning these options, the consumer's utility-maximising choice will depend on his or her preference patterns (how the consumer believes that the different combinations of goods and services will effect his or her total utility).