The role of promotion as a marketing function: what it does and how it fits the mix

Promotion is the marketing function that communicates with the market. Its role is to inform buyers that an offer exists, persuade them that it is the right one, and remind them to return or recommend. It does not decide what the product is, what it costs or where it is sold. Those belong to the other three mix decisions. Promotion makes the other three known, understood and wanted.

This page sets out the five jobs promotion does, the tools it uses, how to choose between them, and how to judge whether the function is working. For filled in examples of single promotions, see the marketing promotion sample page.

The place of promotion in the marketing mix

The marketing mix has four decisions: product, price, place and promotion. The first three create the offer. Promotion carries it to the buyer. A strong product with weak promotion is unknown, and a weak product with strong promotion is bought once. The marketing mix guide shows how the four are set together, and why promotion is usually decided last, after the other three are fixed.

The five jobs of promotion

1. Inform. Tell the market the offer exists: what it is, who it is for, what it costs and where to get it. For a new product this is the largest job.
2. Persuade. Give the buyer reasons to choose this offer over others: evidence, proof, comparison, social proof.
3. Remind. Keep the brand present between purchases so that when the need returns, the name comes to mind first.
4. Differentiate. Make the offer look and sound unlike its alternatives, so price is not the only thing left to compare.
5. Build the brand. Over years, accumulate a consistent set of associations, so that every later message starts with trust already in place.

The five promotion tools

Tool	What it does	Strongest at
Advertising	Paid, controlled messages in media	Reach and repetition
Sales promotion	Short term incentives such as discounts and samples	Prompting a purchase now
Personal selling	One to one conversations	Complex or high value sales
Public relations	Earned coverage and reputation work	Credibility
Direct and digital marketing	Email, search, social and content aimed at identifiable people	Measurable response

Together these form the promotion mix. Most businesses use three or four of them, and the proportions change as the product ages.

How the role changes through the product life

• Launch. Inform dominates. Use publicity, content and trials to build awareness.
• Growth. Persuade dominates. Competitors arrive, so proof and comparison carry the weight.
• Maturity. Remind and differentiate dominate. Loyalty offers and brand work protect share.
• Decline. Spend falls to what the remaining loyal buyers justify.

Choosing the tools for a job

Three questions decide the mix. First, how much does the buyer need to be persuaded? High value, high risk purchases need personal selling and proof. Low value, habitual ones respond to advertising and reminders. Second, where is the buyer in the journey? Unaware buyers need awareness tools, and warm buyers need offers. Third, what can you measure? Prefer tools that let you see response, and set the number to watch before spending begins.

The inbound and outbound marketing page covers one common split in how these tools are used, and traditional and digital marketing covers another.

Judging whether promotion is doing its job

1. Set one objective per campaign: awareness, enquiries, trial or repeat purchase.
2. Record a baseline before the campaign starts.
3. Track the number that matches the objective, not the one that is easiest to read.
4. Check the margin after promotion cost. A discount that doubles sales and halves profit has failed its job.
5. Review quarterly and move budget from the tools that missed to the tools that hit.

Questions about the role of promotion

What is the main purpose of promotion?

To communicate the offer so the target buyers know it, understand it and prefer it. The three verbs are inform, persuade and remind.

What is the difference between promotion and advertising?

Advertising is one tool. Promotion is the whole function, which also includes sales promotion, personal selling, public relations and direct marketing.

Why is promotion called a function of marketing?

Because it is a continuing activity with its own objectives, budget and people, one of the standard jobs a marketing department carries out beside research, product development, pricing and distribution.

How much should a business spend on promotion?

Start from the objective and cost it back: how many customers are needed, what it costs to win one, and what that adds up to. Industry rules of thumb give a starting range, and your own cost per customer replaces them within a few months.

Does promotion matter for a service business?

More than for products, because a service cannot be sampled in advance. Reviews, case studies and referrals do the proving.

What the assistants promote on your behalf

Promotion used to mean the messages a business paid for or placed. Buyers now ask an assistant first, and the assistant writes its own version of the promotion: a few sentences about what a business is and whether to pick it, built from sources the business does not control. Ask ChatGPT, Gemini or Perplexity to recommend a supplier in your category and note whether you appear and how you are described. AI Knows Us (aiknowsus.com) runs that question across the assistants and records the wording, so the assistant's version of your promotion sits beside the one you wrote.