The four basic principles of marketing are product, price, place and promotion. These concepts originated in the 1950's and are used by businesses to identify key factors such as what consumers want, how their product or service meets those needs, how their product is perceived, how they differentiate themselves from their competitors, and how they interact with their customers.
Product (the good or service) - presumably, a product should fulfill a consumer demand or otherwise be compelling. Understanding every aspect of the product, including its life cycle, target audience, and where it falls in the context of its industry is important.
Price (what the consumer pays) - pricing a product ideally links it to its real and perceived value, and should also consider supply costs, discounts, and competitive pricing.
Place (location/channel where the product is marketed) - where a product is marketed takes into consideration how it is delivered to consumers. It may involve placing a product in stores, where it is displayed, and even placing it on TV shows, films or web pages.
Promotion (advertising the product) - promotion includes advertising, public relations, and advertising strategy, and ties into the other three P's.