Advertising Explained: What It Is and What It Does

Advertising is paid communication designed to change what people think, feel, or do in relation to a brand, product, or service. It operates across channels, from television to paid search, but the underlying function is consistent: put a message in front of an audience and influence their behaviour over time.

That sounds simple enough. But in practice, advertising is one of the most misunderstood investments a business makes. Most companies confuse activity with effect, and most measurement systems are built to confirm what people already believe rather than reveal what is genuinely happening.

What Advertising Actually Means as a Business Function

Advertising sits within a broader commercial system. It is not a standalone discipline. It connects to pricing, distribution, product quality, and sales capacity. When those elements are misaligned, advertising cannot fix them. It can amplify what is already there, good or bad, but it cannot substitute for a product people do not want or a price point that does not make sense.

I have spent time in rooms where advertising was being asked to solve problems it was never designed to solve. A retailer with a distribution problem does not need a bigger media budget. A brand with a trust deficit does not need a cleverer tagline. Advertising is most powerful when the rest of the commercial model is working, and it is asked to do one specific thing: reach more of the right people with a message that matters to them.

This is worth stating plainly because it changes how you evaluate advertising decisions. The question is not just “what should we say?” It is “what role does advertising need to play in this business at this moment?” That framing sits at the heart of any serious go-to-market and growth strategy, and it is the framing that most briefs skip entirely.

The Two Jobs Advertising Has Always Had

There is a persistent debate in marketing about brand versus performance, awareness versus conversion, long-term versus short-term. In practice, advertising has always had two jobs running simultaneously, and the tension between them is where most budget decisions go wrong.

The first job is to build memory structures. This means reaching people who are not currently in the market for what you sell and making your brand easy to recall when they eventually are. Most purchase decisions are not made in the moment of exposure to an ad. They are made weeks, months, or years later, and what determines the outcome is which brands feel familiar, trusted, and relevant at that moment of decision. Advertising does not close that sale directly. It creates the conditions for it.

The second job is to activate existing demand. This means reaching people who are already in the market and giving them a reason to choose you now. Search advertising, retargeting, promotional emails, and price-led display campaigns all operate in this space. They are efficient because the audience is already motivated. But they are limited because they are competing for a pool of demand that already exists, rather than expanding it.

Earlier in my career I overweighted the second job. Performance marketing was delivering numbers that looked compelling, and it was easy to credit those numbers to the advertising. What I came to understand, over time, is that much of what performance channels claimed credit for was going to happen anyway. The customer had already made up their mind. The brand had already done its work, often through channels that were harder to measure. The paid click was the last step in a much longer experience, not the cause of the sale.

Think about a clothes shop. Someone who tries on a garment is far more likely to buy it than someone who just browses. The fitting room did not create the desire to buy clothes. It resolved a specific uncertainty at a specific moment. Performance advertising often plays the role of the fitting room. It is valuable, but it is not where the desire was built.

How Advertising Creates Commercial Value

Advertising creates commercial value through three mechanisms, and understanding them separately matters because each requires a different approach to planning, buying, and measurement.

The first is reach. Getting your message in front of people who have not encountered your brand, or have not thought about it recently, is the foundational act of advertising. Without reach, everything else is optimising a shrinking pool. BCG’s work on commercial transformation has consistently pointed to reach and relevance as the twin engines of growth, particularly for brands trying to expand beyond their existing customer base.

The second is salience. This is the quality of being easy to think of in a buying situation. Salience is built through repetition, distinctive assets, and consistent presence over time. It is not the same as awareness. A brand can be well known and still lose at the point of purchase because a competitor feels more immediately relevant. Advertising builds salience by associating a brand with the right cues, the situations, emotions, and problems that trigger a purchase decision.

The third is persuasion. This is the most talked about function of advertising and probably the least reliable. Persuasion through a single ad exposure is rare. What advertising does more consistently is reinforce existing beliefs, reduce uncertainty, and create permission for a decision that was already forming. The persuasive power of advertising is cumulative, not instantaneous.

When I was running an agency and we were presenting campaign effectiveness to clients, the most honest conversations were always about which of these three things the work was actually doing. Conflating them leads to bad decisions. A brand awareness campaign judged on conversion rates will always look like it failed. A performance campaign judged on long-term brand equity will always look irrelevant. The metric has to match the mechanism.

What Advertising Is Not

It is worth being clear about the boundaries, because the word advertising gets used to cover a lot of things it does not actually describe.

Advertising is not content marketing, though content can be used in advertising. Content marketing operates on a different logic: it earns attention through utility or entertainment rather than buying placement. The distinction matters for budgeting, measurement, and creative approach.

Advertising is not public relations, though both can shape perception. PR works through editorial endorsement and earned media. Advertising controls the message and pays for placement. One is borrowed credibility. The other is owned communication.

Advertising is not a substitute for product quality, pricing strategy, or distribution. I have seen brands spend significant budgets advertising products that had fundamental problems. The advertising sometimes delayed the inevitable by a quarter or two, but it never fixed the underlying issue. Advertising amplifies. It does not correct.

And advertising is not the same as marketing. Marketing is the broader commercial discipline: understanding customers, defining positioning, setting prices, choosing channels, building relationships. Advertising is one tool within that system. Treating advertising as synonymous with marketing is one of the reasons so many marketing functions end up being measured on the wrong things.

The Role of Channels in Advertising

Channels are the means of delivery, not the strategy. This is a distinction that gets lost constantly, particularly in conversations about digital advertising where the channel options have multiplied to the point of distraction.

Television, radio, outdoor, print, digital display, paid social, paid search, connected TV, podcast advertising, influencer partnerships: each has a different relationship with attention, a different audience profile, and a different cost structure. Choosing between them is a planning question, not a strategy question. The strategy comes first: who needs to know what, and what do we want them to do as a result?

One of the most common mistakes I see in media planning is channel selection driven by familiarity or internal capability rather than audience behaviour. A business with a strong paid search team will often default to search even when the growth opportunity requires reaching people who are not yet searching. Vidyard’s analysis of why go-to-market feels harder makes a related point: the channels that are easiest to measure are not always the channels that are doing the most work.

The right channel mix depends on where your audience is, what they are doing when they encounter your message, and what kind of response you are trying to generate. A high-consideration B2B purchase requires a different channel strategy than a low-cost consumer impulse buy. Neither is more sophisticated than the other. They are just different problems.

How Advertising Fits Into a Growth Strategy

Advertising is a growth lever, but it is not the only one and it is not always the right one. Understanding where it fits in a broader growth model is what separates disciplined marketing investment from activity for its own sake.

Growth comes from three sources: acquiring new customers, retaining existing ones, and increasing the value of those relationships over time. Advertising is most directly associated with acquisition, but it plays a role in retention too. Brands that maintain consistent advertising presence among existing customers see stronger retention than those who go dark after the sale. The advertising is not selling anything new. It is reinforcing the decision the customer already made and reducing the likelihood they will reconsider.

BCG’s research on go-to-market strategy in financial services found that brands consistently visible to existing customers during non-purchase periods maintained significantly stronger share of wallet than those who only communicated at renewal or repurchase moments. The same principle applies across categories.

When I grew an agency from a bottom-five position to a top-five position in its market, a significant part of that involved being more deliberate about which growth levers we were pulling at which stage. In the early phase, advertising was less important than reputation, referral, and case study development. As the agency scaled, advertising became more relevant because we needed to reach buyers who had no existing connection to us. The role of advertising changed as the business changed. That is how it should work.

If you are thinking about how advertising connects to your broader commercial model, the Go-To-Market and Growth Strategy hub covers the full picture: from market entry to scaling, from positioning to channel selection. Advertising is one piece of that system, and it works best when it is designed as part of the system rather than bolted on at the end.

What Good Advertising Looks Like in Practice

Good advertising is not necessarily clever advertising. It is not award-winning advertising. It is advertising that does the job it was designed to do, reliably, over time.

I have judged the Effie Awards, which recognise advertising effectiveness rather than creative craft. The work that wins is not always the work that wins at Cannes. Sometimes it is straightforward, even plain. What it always has is a clear objective, a well-defined audience, and evidence that it moved something meaningful in the business. That combination is rarer than it should be.

Good advertising starts with a clear brief. Not a brief that describes the product in detail, but a brief that describes the audience, their current relationship with the brand, and the specific thing the advertising needs to change. Most briefs I have read in twenty years spend too much time on the former and too little on the latter.

Good advertising is also consistent. Not repetitive in a lazy sense, but consistent in the sense of building on a coherent brand identity over time. The brands with the strongest advertising track records, the ones that have compounded their brand value over decades, are almost never the ones that reinvented themselves every two years. They found something true about their brand, expressed it in a way that connected with their audience, and kept building on it.

Early in my career, I was in a brainstorm for Guinness at a new agency. The founder had to leave for a client meeting and handed me the whiteboard pen. I remember thinking: this brand has one of the most consistent advertising identities in the world, and here I am trying to add something to it. The lesson I took from that session was not about the specific ideas we generated. It was about the discipline required to add to a brand rather than disrupt it. Most advertising briefs ask for disruption when they should be asking for contribution.

The Measurement Problem in Advertising

Advertising measurement is one of the most contested areas in marketing, and for good reason. The tools available to measure advertising effectiveness are imperfect, and the incentives in the industry push consistently toward overclaiming.

Digital advertising created the impression that everything could be measured precisely. Last-click attribution, view-through conversions, impression-to-sale tracking: these tools are useful, but they are not the same as understanding what advertising actually caused. They measure correlation within a defined window. They do not measure the cumulative effect of brand-building, the role of advertising in creating the conditions for a sale that happened six months later, or the counterfactual of what would have happened without the advertising at all.

Tools like those covered in Semrush’s analysis of growth tools can help marketers understand channel performance, but they are a perspective on reality rather than reality itself. The measurement system you use shapes the decisions you make. If your measurement system overcredits performance channels, you will underinvest in brand. If it only measures short-term conversion, you will systematically undervalue the advertising that is building your long-term position.

The honest answer is that advertising measurement requires a portfolio of approaches: marketing mix modelling for macro-level understanding, brand tracking for perception shifts, incrementality testing for specific channel decisions, and qualitative research for the things that numbers cannot capture. No single tool gives you the full picture. Anyone who tells you otherwise is selling something.

Managing hundreds of millions in ad spend across thirty industries gave me a particular scepticism about measurement certainty. The clients who made the best long-term decisions were not the ones with the most sophisticated attribution models. They were the ones who understood the limitations of their data and made honest approximations rather than false precision.

Common Advertising Mistakes Worth Avoiding

There are patterns that show up repeatedly in advertising decisions, regardless of industry or budget size.

The first is optimising for the metric rather than the outcome. When a campaign is judged on click-through rate, the creative gets optimised for clicks. When it is judged on cost per acquisition, the targeting gets narrowed to the most likely converters. Both of these optimisations can improve the metric while damaging the underlying business objective. Clicks are not sales. Cheap acquisitions from a narrow audience do not build a scalable customer base.

The second is inconsistent investment. Advertising works through accumulation. A brand that spends heavily for two quarters and then goes dark does not retain the equity it built. The market does not hold your place while you are absent. Competitors fill the space, and the memory structures you built begin to decay. Consistent presence at a lower level often outperforms bursts of heavy spending followed by silence.

The third is mistaking novelty for effectiveness. New formats, new platforms, and new creative approaches attract attention within the industry but do not automatically produce better results for the brand. Semrush’s examples of growth-oriented marketing show that the tactics generating the most industry coverage are rarely the ones delivering the most consistent commercial return. Proven approaches applied with discipline usually outperform experimental approaches applied without it.

The fourth is briefing for entertainment rather than effect. Advertising that entertains is valuable, but entertainment is not the objective. The objective is a commercial outcome. Some of the most effective advertising I have seen is not particularly entertaining. It is clear, relevant, and present at the right moment. That combination works even when the creative is unremarkable.

Understanding these patterns, and building advertising programmes that avoid them, is what separates marketing that compounds over time from marketing that produces activity without accumulation. Crazyegg’s overview of growth-oriented marketing approaches is a useful reference for thinking about how advertising connects to broader commercial growth levers.

About the Author

Keith Lacy is a marketing strategist and former agency CEO with 20+ years of experience across agency leadership, performance marketing, and commercial strategy. He writes The Marketing Juice to cut through the noise and share what works.

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