Critical marketing functions include

1. Identifying the important supporters within the marketplace. Everyone will tell you to focus on customers, former customers and prospects, but there are also groups that set rules and regulations, influence or recommend, establish barriers, service the product after the sale and review the product. All of these groups and more are supporters that play a role in the successful marketing of a product or service.
2. Identifying and valuing specific target purchaser/user groups for the product. (Also known as target audiences or market segments.). Marketing should answer the questions focusing on who will be a likely prospect, who will be the best customer. Keep in mind that within the target audience there may be groups that will be readily obvious as "end users" but there may also be groups that specify, recommend, purchase, service, pay for; without a great stretch of the imagination, they may all be considered customers or prospects.
3. Communicating with the marketplace. This function may involve traditional communications disciplines (public relations, advertising, sales promotion, face to face selling) along side new disciplines (the Internet, social media, text messaging etc.). Each target audience segment within the marketplace may play a different role in the success of marketing so different techniques or disciplines may be required to communicate effectively. Objectives need to be set for each discipline used and for each audience group or segment that is targeted.
4. Conducting transactions with the marketplace. Most people think of marketing activities as advertising or promotional events -- very visible, very costly. But other interactions are part of the marketing process and should be viewed as such. (Here is where the outside-in perspective of marketing plays a vital role.) Order processing is not just an inventory transaction, but a marketing one as well — the timely delivery of a product in good condition goes a long way in helping establish a positive attitude about the company and provides another reason for the end-user to purchase again and to recommend the company and its products to others. Payment processing is not just a financial transaction; it is an important element in the marketing process — payment is what is given in exchange for the item that will satisfy a need (or an itch). Shipping the product is not just the act of putting something in a box and handing it over to UPS; it is a marketing transaction as well — satisfaction with the product or the company is never higher than when the box or envelop is just about to be opened.
5. Obtaining on-going feedback from the marketplace. An important function of marketing is to measure the performance of the enterprise in its efforts to acquire and maintain customers. What does it cost to acquire a customer? What does it cost to obtain the second order or purchase? Establishing performance metrics is often an afterthought in the planning process and, in many instances, superficial.
6. Market share is but one measure of marketing performance. Share of Customer is equally, if not, more important: if a customer purchases 100 units/year from enterprise ‘A’ but purchases 500 units /year in total, enterprise ‘A’ has a Share of Customer of 20%. How much effort should be expended to increase Share of Customer? Or, how much should be spent to maintain the customer at that level?
7. Obtaining feedback also means understanding the environmental conditions that the enterprise operates in, the product is marketed in. Spending on research is essential to direct the development of a product or service and the development of communications messages necessary to acquaint potential customers with the product or service, instill in them positive feelings about the product or service and motivate them to purchase.