Data & identity
Zero-party data
Zero-party data is information a customer intentionally and proactively gives a brand, such as preferences, intentions or quiz answers, rather than data inferred from their behaviour.
The term was popularised by the research firm Forrester to describe data people hand over deliberately. When you tell a beauty retailer your skin type in a quiz, set your preferred football team in a sports app or choose which newsletters you want, that is zero-party data.
Its appeal is clarity: the customer knows they shared it and usually why, so it can be both accurate and easier to use with consent. Brands use it to personalise content, product recommendations and offers, and to reduce reliance on tracking.
In practice, many people treat zero-party data as a subset of first-party data: it is still collected directly by the business, just explicitly declared rather than observed. It is not a legal category, so it still falls under laws such as GDPR and CCPA / CPRA, and a stated preference can still be sensitive, for example health or religion. Declared data can also be aspirational or wrong, so it works best combined with observed behaviour.
Think of it like this
Zero-party data is like a dinner guest telling you in advance they are vegetarian, rather than you guessing from what they left on the plate last time.
An example
A travel app in Thailand asks new users three questions about budget, travel style and favourite destinations; 70% answer, and the app uses the answers to personalise deals.
Related terms
First-party data
First-party data is information a company collects directly from its own customers or audience, such as purchases, sign-ups, app use and site behaviour, through its own channels.
Second-party data
Second-party data is another company's first-party data shared directly with you through a partnership, such as an airline sharing audience insights with a hotel chain.
CDP (customer data platform)
A CDP (customer data platform) is software that collects a company's first-party customer data from many sources, unifies it into individual profiles and makes those profiles available to marketing tools.
Audience segment
An audience segment is a group of people or devices defined by shared characteristics, such as demographics, interests, purchase behaviour or intent, used to target or measure advertising.
Data minimization
Data minimization is the privacy principle that organisations should collect and keep only the personal data that is adequate, relevant and necessary for a specific, stated purpose.
Sources: GDPR Article 5: principles