In it’s most broad definition marketing deals with all the activities that must take place in order to create customers. Another way to slice this definition up is to say that marketing deals with all the one to many communications, where direct sales is a one to one communication.
Things that involve promoting your product to many people at once is marketing. Attending trade shows, advertising, creating literature, figuring out who to market to, what message to use for each market segment, etc. This would also include sales literature.
Sales is able to do it’s job because marketing creates the awareness and demand. Salespeople deal with the customer in a one to one relationship to close the sale. Sales calls, quotes, overcoming objections, and any personal relationship building is the job of sales.
The sales process cannot begin until Marketing has created an awareness of the product or service.
Once all of the Marketing work is done then the sales function converts that work into customers and sales. It is important to note that with so much work performed up front in Marketing that the sales function must perform flawlessly to convert prospects into repeat customers.