Word of Mouth Marketing: Meaning, eWOM and Measurement
Word of mouth marketing is a company's deliberate effort to influence the conversations consumers have with each other about its products, services or brand. The conversation itself belongs to the people having it. A brand can start it, encourage it or put a product in front of people likely to talk. It cannot fully control what gets said, where the message travels or whether the talk turns positive.
Word of Mouth, Word of Mouth Marketing and eWOM
These three terms are often used as if they mean the same thing. They don't.
Word of mouth as communication
In consumer research, word of mouth means informal communication between consumers about products, services and brands. Jonah Berger's 2014 review in the Journal of Consumer Psychology treats the idea broadly: a passing mention counts, not only an explicit recommendation, and the exchange can happen face to face or online. A friend saying a new bakery opened down the street is word of mouth. So is a coworker grumbling about a late delivery.
Word of mouth marketing as a practice
Word of mouth marketing (WOMM) adds intent. In their study of word of mouth marketing in online communities, Robert Kozinets and colleagues (2010) describe WOMM as marketers deliberately using professional techniques to shape how consumers talk to one another. That deliberate influence is the dividing line. Talk that would have happened anyway is word of mouth; a planned effort to prompt or shape it is word of mouth marketing.
Tactics range from giving selected people a product to try to making it easier for customers to share an opinion. None of these tactics guarantees a conversation, let alone a favorable one.
Electronic word of mouth (eWOM)
eWOM is the online branch of the same phenomenon. An early formulation by Thorsten Hennig-Thurau and colleagues (2004), reproduced on Hennig-Thurau's own website, describes eWOM as positive or negative statements by potential, actual or former customers about a product or company, made available to many people and institutions through the internet.
Later work refines the boundaries. In a framework covering eWOM creation, exposure and evaluation, Ana Babić Rosario, Kristine de Valck and Francesca Sotgiu define eWOM as consumer-generated communication about consumption that uses digital tools and is aimed mainly at other consumers. Their definition rests on four elements: who communicates, what the message is about, which digital channel carries it and who receives it.
The same framework separates eWOM from three neighbors. User-generated content in general is broader, because not all of it concerns consumption. Advertising comes from the firm rather than from consumers. Observational learning, where people draw conclusions from what others do rather than from what they say, falls outside eWOM as well. These are attributed frameworks, not a settled taxonomy.
The Four Parts of a Word of Mouth Exchange
The four parts below are an adapted analytical framing for this glossary, drawing on the elements in the eWOM framework above rather than reproducing any single source. Breaking an exchange into parts helps explain why two conversations about one product can differ.
- Source: the person speaking or posting. A current customer, a former customer and a paid partner are different kinds of sources.
- Message: what is actually said, whether a recommendation, a warning, a question or a passing mention.
- Channel: spoken conversation, a group chat, a forum thread, a review site or a social post.
- Audience: one close friend, a small group or a large public following.
Berger's review of word of mouth research in the Annual Review of Psychology notes that word of mouth differs by modality, such as spoken versus written, and by audience, such as talking to one person versus broadcasting to many. Those differences may shape what people choose to say. They do not add up to a single rule about which channel works best.
Mentions, Recommendations and Valence
A common misunderstanding is that word of mouth means praise. It doesn't.
The 2004 eWOM formulation explicitly covers both positive and negative statements, and Berger's 2014 review counts simple mentions alongside recommendations. A customer saying they tried an app last week is part of the conversation, even without a verdict.
When analysts code brand conversations, they may add neutral and mixed categories. That is an analytical choice rather than a category fixed by these definitions, and two coders can reasonably disagree about where a comment belongs.
Negative discussion deserves real attention. Counting only favorable posts distorts the picture of what people are saying. Blanket claims that negative word of mouth always spreads faster or always does more damage are not established as universal rules. Monitoring and answering public criticism belongs to a related discipline, online reputation management.
Where the Conversation Happens
Berger's 2014 review covers both offline and online word of mouth. Three broad contexts are worth separating.
- Offline: face-to-face conversations and phone calls, which often leave no public record.
- Public online: reviews, forums, community threads and public social posts, visible to people outside the conversation.
- Private digital: messaging apps, direct messages and email, which are digital but usually closed to outside observation.
In their study of a campaign that seeded a product with bloggers, Kozinets and colleagues found that the marketing message was not simply repeated. Bloggers reworked it to fit their own stories and the expectations of their communities. A brand taking part in community platforms, for example through Reddit marketing, should plan for its message to be reinterpreted rather than passed along intact.
Who Takes Part
Current customers are the obvious participants. The definitions reach further.
The 2004 eWOM formulation names potential, actual and former customers as possible sources. A former customer explaining why they switched is part of the conversation. So is a prospective buyer asking a forum for advice.
People who never bought the product can matter too. A field study by David Godes and Dina Mayzlin, Firm-Created Word-of-Mouth Communication (2009), examined word of mouth that a firm generated through both customers and noncustomers. That design treats noncustomers as possible senders, but it does not tell a marketer which group works better in a given market.
Firsthand experience can also be a useful distinction for analysts. A recommendation based on using the product is a different kind of statement from a comment that repeats what someone heard, although both can count as word of mouth and the difference is not always visible in the content.
Why People Share, and Why Messages Change
Research reviewed by Berger points to several possible motives for talking about products, including how sharing makes people look to others, the information it lets them pass on or gather, and the social connection it creates. These are possible drivers. They are not requirements.
The same goes for product traits. Berger's 2014 review notes that plenty of everyday conversation concerns ordinary products that happen to be on someone's mind, which challenges the popular idea that a product must be remarkable before anyone mentions it. Quality, novelty or an incentive may make talk more likely in some situations, but none is a proven universal prerequisite.
Messages also change as they move. The Kozinets study showed seeded messages being reframed inside community narratives, and Berger's 2014 review discusses how the person sharing shapes what gets passed on. A brand that briefs fans on three talking points should not expect those points to arrive word for word.
Networks and Weak Ties
People are linked in networks, and word of mouth moves along those links. In Talk of the Network (2001), Jacob Goldenberg, Barak Libai and Eitan Muller discuss strong ties, such as close friends and family within a personal network, and weak ties, the looser acquaintances that connect one personal network to another. They explored how information moves across these ties with a simulation model rather than by tracking real conversations.
That framing helps explain how a message jumps between social circles through a casual acquaintance. It is not evidence that weak ties always outperform strong ones, that one network shape always spreads information faster, or that any single person is a guaranteed amplifier. A model's results depend on its assumptions.
Observing and Measuring Word of Mouth
Measurement raises two challenges.
The first is visibility. David Godes and Dina Mayzlin, in Using Online Conversations to Study Word-of-Mouth Communication (2004), point out that word of mouth is hard to study because many conversations happen in private. A count of visible mentions is therefore likely to be a partial view.
The second is the direction of cause. The same paper raises the concern that word of mouth may reflect past sales rather than drive future ones. A product that sells well gets talked about. That alone does not prove the talk produced the sales.
A practical safeguard is to measure separate things separately. The breakdown below is an analytical framework for planning, not a validated causal model:
- Communication: did people talk or post about the brand, and what did they say?
- Exposure: who saw or heard those messages? This is the step closest to brand awareness, but exposure alone does not show that anyone remembers the brand.
- Intention: do people say they would recommend or buy? Net Promoter Score captures a stated intention to recommend, not an observed conversation.
- Referrals: was a tracked referral link or code actually used?
- Conversion: did a purchase or sign-up follow, and can it be connected to the conversation at all?
Hypothetical example: a neighborhood café sees more mentions in local community posts after launching a seasonal drink. That supports a statement about communication. It does not show that more people visited because of the posts, since the drink itself, the weather or a rise in visits already under way could explain both.
Commercial Involvement and Disclosure in the United States
Once a brand gives something of value to the people talking, the conversation changes character. In the United States, the Federal Trade Commission (FTC) addresses this in several documents. The summary below is for orientation only. It is not legal advice and does not describe rules in Indonesia, the European Union, the United Kingdom or any other jurisdiction.
- Material connections: the FTC's Disclosures 101 for Social Media Influencers (November 2019) tells people who endorse a brand to disclose any financial, employment, personal or family relationship with it, and explains that free or discounted products can count as a financial relationship.
- Audience expectation: under the FTC Endorsement Guides (16 CFR Part 255), a connection must be disclosed when the audience would not reasonably expect it and it could materially affect the weight or credibility given to the endorsement.
- Honest opinions: the same Guides say endorsements must reflect the endorser's honest opinions, findings, beliefs or experience, a principle carried forward in the 2023 Federal Register notice of the revised Guides.
- Legal status: the Endorsement Guides describe themselves as administrative interpretations of how Section 5 of the FTC Act applies to endorsements, not a separate statute.
- Review incentives: FTC staff's questions and answers on the Consumer Reviews and Testimonials Rule explain that a business may not offer an incentive conditioned on a review expressing a particular sentiment, positive or negative, while not treating every review incentive as prohibited. The Q&A is staff guidance, not the binding rule text, and incentivized reviews can still raise disclosure questions under the Endorsement Guides.
In practice, three situations are worth keeping apart, without treating them as a formal classification. When a brand prompts consumer talk, for example by giving someone a free product, the result is still a conversation, but in the United States that material connection should be disclosed when the audience would not reasonably expect it and it could affect the weight they give the message. A commercial endorsement, such as paid creator content, carries the same disclosure expectation. Talk that happens later among people who have no connection to the brand is ordinary consumer communication, even if it started from prompted or paid content. This is where word of mouth marketing overlaps with influencer marketing services and other paid creator work.
How Word of Mouth Marketing Differs From Related Concepts
The boundaries below are editorial choices for this glossary; industry usage varies.
| Concept | Main focus | Boundary with word of mouth marketing |
|---|---|---|
| Brand advocacy | Supportive relationships with people who actively back a brand | Word of mouth also includes criticism and non-advocates |
| Referral marketing | A structured mechanism for gaining customers through existing ones | Word of mouth covers discussion that may never involve a referral program |
| Social proof | How people read visible evidence of others' choices and opinions | Word of mouth is the act of communication; social proof is one way its traces are read |
| Viral marketing | Rapid, wide spread of a message or content | Usage overlaps, but word of mouth does not require speed or scale |
| Influencer marketing | Relationships between brands and creators | A brand-linked creator post is not automatically independent word of mouth |
| User-generated content | Any content made by users | In the eWOM framework above, eWOM must be about consumption |
| Reviews | A format of consumer communication | Can be word of mouth; incentives and material connections raise endorsement issues |
| Net Promoter Score | Survey of stated likelihood to recommend | Measures intention, not observed conversation |
| Buzz marketing | Efforts to create talk or attention around a brand | Definitions vary; not treated here as a fixed subtype |
Frequently Asked Questions
What is word of mouth marketing?
Word of mouth marketing is a company's deliberate effort to influence the conversations consumers have with each other about its products, services or brand, offline and online. The conversation belongs to consumers. It can be positive or negative, and the company cannot fully control it.
How is word of mouth marketing different from word of mouth?
Word of mouth is the communication itself: people mentioning, recommending or criticizing a brand to each other. Word of mouth marketing is the practice of trying to encourage or shape that communication on purpose. Kozinets and colleagues use this deliberate influence as the dividing line.
What is electronic word of mouth (eWOM)?
eWOM is word of mouth carried by digital tools such as reviews, forums, social posts and messaging. A 2004 formulation by Hennig-Thurau and colleagues covers positive or negative statements by potential, actual or former customers shared online. A later framework adds that eWOM is consumer-generated, about consumption and aimed mainly at other consumers.
Does negative discussion count as word of mouth?
Yes. The 2004 eWOM formulation explicitly includes negative statements, and broader reviews count simple mentions as well as recommendations. Tracking only praise distorts the picture. No universal rule establishes that negative word of mouth always spreads faster or does more harm.
Who can spread word of mouth about a brand?
Current, potential and former customers can all be sources, and research has examined firm-created word of mouth spread through noncustomers. It helps to note whether a speaker has firsthand experience with the product and any material connection to the brand.
How can word of mouth be measured?
Measure separate things separately: the conversation, exposure to it, stated intentions, tracked referrals and conversions. Private conversations are hard to observe, and word of mouth may reflect past sales rather than cause new ones, so visible mention counts alone do not prove impact.
Can a brand offer incentives for reviews or posts?
In the United States, FTC guidance does not ban every incentive. Under the Endorsement Guides, a material connection such as payment or a free product should be disclosed clearly and conspicuously when the audience would not reasonably expect it and it could affect the weight they give the message. Separately, FTC staff guidance on the Consumer Reviews and Testimonials Rule explains that a business may not offer an incentive for a consumer review that is conditioned on the review expressing a particular sentiment. That restriction concerns consumer reviews, not every post or testimonial. Rules differ elsewhere, and this is not legal advice.
Sources and Related Terms
References
- Kozinets, R. V., et al. (2010). Networked Narratives: Understanding Word-of-Mouth Marketing in Online Communities. Journal of Marketing. Publisher abstract
- Hennig-Thurau, T. Electronic word-of-mouth, author page reproducing the 2004 definition by Hennig-Thurau et al. Author website
- Babić Rosario, A., de Valck, K., & Sotgiu, F. Conceptualizing the electronic word-of-mouth process: What we know and need to know about eWOM creation, exposure, and evaluation (manuscript version of the 2020 article). HEC Paris PDF
- Berger, J. Review of word of mouth research, Annual Review of Psychology (author-hosted PDF). Wharton faculty PDF
- Berger, J. (2014). Word of mouth and interpersonal communication: A review and directions for future research. Journal of Consumer Psychology. Wharton faculty PDF
- Godes, D., & Mayzlin, D. (2004). Using Online Conversations to Study Word-of-Mouth Communication. Marketing Science. INFORMS publisher page
- Godes, D., & Mayzlin, D. (2009). Firm-Created Word-of-Mouth Communication: Evidence from a Field Test. Marketing Science. INFORMS publisher page
- Goldenberg, J., Libai, B., & Muller, E. (2001). Talk of the Network: A Complex Systems Look at the Underlying Process of Word-of-Mouth. Marketing Letters. Columbia Business School PDF
- U.S. Federal Trade Commission (2019). Disclosures 101 for Social Media Influencers. FTC business guidance
- Guides Concerning the Use of Endorsements and Testimonials in Advertising, 16 CFR Part 255. eCFR
- U.S. Federal Trade Commission (2023). Guides Concerning the Use of Endorsements and Testimonials in Advertising, final revised Guides, Federal Register document 2023-14795. Federal Register public inspection PDF
- U.S. Federal Trade Commission. Consumer Reviews and Testimonials Rule: Questions and Answers. FTC business guidance
