Marketing is the activity, set of institutions, and processes for creating, communicating, delivering, and exchanging offerings that have value for customers, clients, partners, and society at large. From this definition, I hope it is clear to you that successful marketing creates value for two or more parties so that each is satisfied.
The definition goes much deeper than simply "selling something to somebody", however, the definition demands an exchange and in this day and age when we no longer barter for goods or services and we have common currencies, that exchange is called a sale.
So while the goal of marketing is sell something, this transaction should not be through coersion and both parties should emerge from the transaction highly satisfied. Satisfaction of both parties is an implicit aspect in the exchange relationship. Marketing must understand both the "Needs & Wants" side of the equation and the "Product, Ideas, & Services" side of the equation.
Not only must marketing fully understand both sides of the equation, but it must also effectively communicate the details of each in order to successfully bridge the gap between the two. Marketing Strategy is a set of specific ideas and actions that outline and guide decisions on the best or chosen way to create, distribute, promote, and price a product or service (manage the marketing mix variables).