# Third-Party Data

**Category:** general  
**Short Description:** External data acquired from providers to enhance audience targeting and insights.  
**Last Updated:** 2026-05-30T00:00:00Z

## Definition

Third-party data is information purchased or acquired from external providers who collect data across various sources and websites. This data helps expand targeting capabilities beyond first-party data, providing additional demographic, behavioral, and interest-based insights for audience targeting and market analysis.

## Examples

- Demographic enrichment of customer profiles
- Interest-based audience targeting
- Market research and competitive analysis
- Look-alike modeling data enhancement

## FAQs

### What is third-party data?

Third-party data is audience information aggregated from many sources by data brokers and sold to advertisers, who have no direct relationship with the people it describes. It historically powered broad audience targeting — interest and demographic segments compiled across the web — letting advertisers reach people based on data they didn't collect themselves. Its availability and reliability are now declining sharply.

### Why is third-party data declining?

Because the tracking it relied on is being dismantled: browsers are deprecating third-party cookies, mobile platforms restrict cross-app tracking, and privacy regulations (GDPR, CCPA and successors) limit collection and sharing without consent. Together these erode the cross-site tracking that third-party data depended on, reducing its coverage and accuracy and pushing the industry toward first-party data and privacy-safe alternatives.

### How was third-party data used in advertising?

Mainly for prospecting and audience targeting at scale — reaching people matching purchased interest, demographic, or behavioral segments compiled by brokers, and for ad-targeting and measurement across the open web. It let advertisers target audiences beyond their own customers without first-hand data. As it declines, those use cases are shifting to first-party data, contextual targeting, and platform algorithms.

### How does third-party data compare to first-party data?

First-party data is collected directly from your own audience — accurate, relevant, owned, and (with consent) durable and compliant. Third-party data is bought from brokers, describes people you have no relationship with, and is broader but less accurate, less durable, and increasingly restricted. First-party is the reliable foundation; third-party is the fading supplement. The clear trend is to invest in first-party and reduce dependence on third-party.

### What replaces third-party data?

A combination: first-party data (collected directly, with consent), contextual targeting (matching ads to page content rather than tracked individuals), platform algorithms that optimize delivery from conversion signals, privacy-preserving approaches (clean rooms, aggregated measurement, modeled conversions), and second-party data partnerships. The post-cookie strategy leans on owned first-party data plus contextual and algorithmic methods rather than broker-supplied individual tracking.

## Related Terms

### Similar Terms

- **[First-Party Data](/resources/glossary/general/first-party-data)**: Direct customer data that third-party data enhances

### Child Terms

- **[Audience Targeting](/resources/glossary/general/audience-targeting)**: Strategic use of various data sources for targeting