In perfect competition or a monopoly advertising may not be necessary. However oligopolies and monopolistic competition can benefit from advertising! The question is what advertising will achieve optimal results. Firms that produce and sell highly differentiated products(perfume, cereal, etc) tend to spend, on average, between 10-20 percent of their revenue on advertising. Industrial related firms however spend hardly any on advertisements. Many economists believe that advertising alters consumers perceptions of a commercial product. For example a coke commercial on tv has hardly any information in it, but everyone in the commercial is at a party with several friends laughing and being happy. Therefore they’re trying to sell an experience causing customers to think “if I drink coke, I can be happy like those people with partying with all their friends.” If you ask me, this is ridiculous. Yes, coke and pepsi taste different, several brands have a difference in quality. But ibuprofen and advil and remotely the EXACT same thing. You don’t need to spend an extra $5 on a sugar coated ibuprofen. Long story short, if consumers are gullible enough to fall into these ludicrous advertisements, more power to the company. I however will be saving my 80 cents getting kroger kidney beans as opposed to del monte. The other side of economists debate defends advertising. Many advertisements contain actual information, whoa! Often advertising offers information to consumers and thus can make better, educated decisions. Consumers(Like me!) who do view advertisements containing information can then take advantage of price differences. How exciting:) So this all being said I learned something new in relation to advertising. Which is most definitely the most intriguing part of the current chapter i’m on. Advertising can actually be a signal of quality. I had never considered this, perhaps it's settled into my subconscious. So to keep things simple i’m going to use the example Mankiw provided. Any other cheap college students out there appreciate cereal? Oh good. Consider General Mills and Kellogg's. They both come out with a new kind of breakfast cereal. So no they must decide if it is beneficial to spend assets on advertising. Kellogs decides they will, because they know their cereal tastes amazing, and if consumers try it once, they are likely to purchase it again(repeat sales, loyalty, etc). In other words, they are confident in their product. General Mills however fears that they will only lose money advertising because while consumers will buy it to try, it’s particularly tasty, thus it is highly unlikely anyone will purchase this product a second time. If this is the case General Mills should just go back to the kitchen and improve the recipe. Consumers know advertising costs companies a great portion of money, and if the company is willing to spend that much on something they believe it must be worth a shot for customers. Overtime consumers would learn to ignore cheap advertising and perhaps find brand loyalty(to kellogg's as opposed to General Mills).